Description:

There is a possible ReDoS vulnerability in the block_format helper in Action Mailer. This vulnerability has been assigned the CVE identifier CVE-2024-47889.

Impact

Carefully crafted text can cause the block_format helper to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade or apply the relevant patch immediately.

Ruby 3.2 has mitigations for this problem, so Rails applications using Ruby 3.2 or newer are unaffected. Rails 8.0.0.beta1 requires Ruby 3.2 or greater so is unaffected.

Releases

The fixed releases are available at the normal locations.

Workarounds

Users can avoid calling the block_format helper or upgrade to Ruby 3.2.

Credits

Thanks to ooooooo_q for the report!

Description:

There is a strong parameters bypass vector in ActionPack.

Versions Affected: rails <= 6.0.3 Not affected: rails < 4.0.0 Fixed Versions: rails >= 5.2.4.3, rails >= 6.0.3.1

Impact

In some cases user supplied information can be inadvertently leaked from Strong Parameters. Specifically the return value of each, or each_value, or each_pair will return the underlying "untrusted" hash of data that was read from the parameters. Applications that use this return value may be inadvertently use untrusted user input.

Impacted code will look something like this:

def update
  # Attacker has included the parameter: `{ is_admin: true }`
  User.update(clean_up_params)
end

def clean_up_params
   params.each { |k, v|  SomeModel.check(v) if k == :name }
end

Note the mistaken use of each in the clean_up_params method in the above example.

Workarounds

Do not use the return values of each, each_value, or each_pair in your application.

Description:

It is possible to possible to, given a global CSRF token such as the one present in the authenticity_token meta tag, forge a per-form CSRF token for any action for that session.

Versions Affected: rails < 5.2.5, rails < 6.0.4 Not affected: Applications without existing HTML injection vulnerabilities. Fixed Versions: rails >= 5.2.4.3, rails >= 6.0.3.1

Impact

Given the ability to extract the global CSRF token, an attacker would be able to construct a per-form CSRF token for that session.

Workarounds

This is a low-severity security issue. As such, no workaround is necessarily until such time as the application can be upgraded.

Description:

There is a possible information disclosure / unintended method execution vulnerability in Action Pack which has been assigned the CVE identifier CVE-2021-22885.

Versions Affected: >= 2.0.0. Not affected: < 2.0.0. Fixed Versions: 6.1.3.2, 6.0.3.7, 5.2.4.6, 5.2.6

Impact

There is a possible information disclosure / unintended method execution vulnerability in Action Pack when using the redirect_to or polymorphic_url helper with untrusted user input.

Vulnerable code will look like this:

redirect_to(params[:some_param])

All users running an affected release should either upgrade or use one of the workarounds immediately.

Workarounds

To work around this problem, it is recommended to use an allow list for valid parameters passed from the user. For example:

private def check(param)
  case param
  when "valid"
    param
  else
    "/"
  end
end

def index
  redirect_to(check(params[:some_param]))
end

Or force the user input to be cast to a string like this:

def index
  redirect_to(params[:some_param].to_s)
end

Description:

There is a possible DoS vulnerability in the Token Authentication logic in Action Controller. This vulnerability has been assigned the CVE identifier CVE-2021-22904.

Versions Affected: >= 4.0.0 Not affected: < 4.0.0 Fixed Versions: 6.1.3.2, 6.0.3.7, 5.2.4.6, 5.2.6

Impact

Impacted code uses authenticate_or_request_with_http_token or authenticate_with_http_token for request authentication. Impacted code will look something like this:

class PostsController < ApplicationController
  before_action :authenticate

  private

  def authenticate
    authenticate_or_request_with_http_token do |token, options|
      # ...
    end
  end
end

All users running an affected release should either upgrade or use one of the workarounds immediately.

Releases

The fixed releases are available at the normal locations.

Workarounds

The following monkey patch placed in an initializer can be used to work around the issue:

module ActionController::HttpAuthentication::Token
  AUTHN_PAIR_DELIMITERS = /(?:,|;|\t)/
end

Description:

There is a possible regular expression based DoS vulnerability in Action Dispatch. This vulnerability has been assigned the CVE identifier CVE-2023-22792.

Versions Affected: >= 3.0.0 Not affected: < 3.0.0 Fixed Versions: 6.1.7.1, 7.0.4.1

Impact

Specially crafted cookies, in combination with a specially crafted XFORWARDEDHOST header can cause the regular expression engine to enter a state of catastrophic backtracking. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should either upgrade or use one of the workarounds immediately.

Workarounds

We recommend that all users upgrade to one of the FIXED versions. In the meantime, users can mitigate this vulnerability by using a load balancer or other device to filter out malicious XFORWARDEDHOST headers before they reach the application.

Description:

There is a possible regular expression based DoS vulnerability in Action Dispatch related to the If-None-Match header. This vulnerability has been assigned the CVE identifier CVE-2023-22795.

Versions Affected: All Not affected: None Fixed Versions: 6.1.7.1, 7.0.4.1

Impact

A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophic backtracking, when on a version of Ruby below 3.2.0. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should either upgrade or use one of the workarounds immediately.

Workarounds

We recommend that all users upgrade to one of the FIXED versions. In the meantime, users can mitigate this vulnerability by using a load balancer or other device to filter out malicious If-None-Match headers before they reach the application.

Users on Ruby 3.2.0 or greater are not affected by this vulnerability.

Description:

The redirect_to method in Rails allows provided values to contain characters which are not legal in an HTTP header value. This results in the potential for downstream services which enforce RFC compliance on HTTP response headers to remove the assigned Location header. This vulnerability has been assigned the CVE identifier CVE-2023-28362.

Versions Affected: All. Not affected: None Fixed Versions: 7.0.5.1, 6.1.7.4

Impact

This introduces the potential for a Cross-site-scripting (XSS) payload to be delivered on the now static redirection page. Note that this both requires user interaction and for a Rails app to be configured to allow redirects to external hosts (defaults to false in Rails >= 7.0.x).

Releases

The FIXED releases are available at the normal locations.

Workarounds

Avoid providing user supplied URLs with arbitrary schemes to the redirect_to method.

Description:

There is a possible ReDoS vulnerability in the query parameter filtering routines of Action Dispatch. This vulnerability has been assigned the CVE identifier CVE-2024-41128.

Impact

Carefully crafted query parameters can cause query parameter filtering to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade or apply the relevant patch immediately.

Ruby 3.2 has mitigations for this problem, so Rails applications using Ruby 3.2 or newer are unaffected. Rails 8.0.0.beta1 depends on Ruby 3.2 or greater so is unaffected.

Releases

The fixed releases are available at the normal locations.

Workarounds

Users on Ruby 3.2 are unaffected by this issue.

Credits

Thanks to scyoon for the report and patches!

Description:

There is a possible ReDoS vulnerability in Action Controller's HTTP Token authentication. This vulnerability has been assigned the CVE identifier CVE-2024-47887.

Impact

For applications using HTTP Token authentication via authenticate_or_request_with_http_token or similar, a carefully crafted header may cause header parsing to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade or apply the relevant patch immediately.

Ruby 3.2 has mitigations for this problem, so Rails applications using Ruby 3.2 or newer are unaffected. Rails 8.0.0.beta1 depends on Ruby 3.2 or greater so is unaffected.

Releases

The fixed releases are available at the normal locations.

Workarounds

Users on Ruby 3.2 are unaffected by this issue.

Credits

Thanks to scyoon for reporting

Description:

There is a possible file content disclosure vulnerability in Action View. This vulnerability has been assigned the CVE identifier CVE-2019-5418.

Versions Affected: All. Not affected: None. Fixed Versions: 6.0.0.beta3, 5.2.2.1, 5.1.6.2, 5.0.7.2, 4.2.11.1

Impact

There is a possible file content disclosure vulnerability in Action View. Specially crafted accept headers in combination with calls to render file: can cause arbitrary files on the target server to be rendered, disclosing the file contents.

The impact is limited to calls to render which render file contents without a specified accept format. Impacted code in a controller looks something like this:

class UserController < ApplicationController
  def index
    render file: "#{Rails.root}/some/file"
  end
end

Rendering templates as opposed to files is not impacted by this vulnerability.

All users running an affected release should either upgrade or use one of the workarounds immediately.

Releases

The 6.0.0.beta3, 5.2.2.1, 5.1.6.2, 5.0.7.2, and 4.2.11.1 releases are available at the normal locations.

Workarounds

This vulnerability can be mitigated by specifying a format for file rendering, like this:

class UserController < ApplicationController
  def index
    render file: "#{Rails.root}/some/file", formats: [:html]
  end
end

In summary, impacted calls to render look like this:

render file: "#{Rails.root}/some/file"

The vulnerability can be mitigated by changing to this:

render file: "#{Rails.root}/some/file", formats: [:html]

Other calls to render are not impacted.

Alternatively, the following monkey patch can be applied in an initializer:

$ cat config/initializers/formats_filter.rb
# frozen_string_literal: true

ActionDispatch::Request.prepend(Module.new do
  def formats
    super().select do |format|
      format.symbol || format.ref == "*/*"
    end
  end
end)

Credits

Thanks to John Hawthorn john@hawthorn.email of GitHub

Description:

There is a potential denial of service vulnerability in actionview. This vulnerability has been assigned the CVE identifier CVE-2019-5419.

Impact

Specially crafted accept headers can cause the Action View template location code to consume 100% CPU, causing the server unable to process requests. This impacts all Rails applications that render views.

All users running an affected release should either upgrade or use one of the workarounds immediately.

Workarounds

This vulnerability can be mitigated by wrapping render calls with respond_to blocks. For example, the following example is vulnerable:

class UserController < ApplicationController
  def index
    render "index"
  end
end

But the following code is not vulnerable:

class UserController < ApplicationController
  def index
    respond_to |format|
      format.html { render "index" }
    end
  end
end

Implicit rendering is impacted, so this code is vulnerable:

class UserController < ApplicationController
  def index
  end
end

But can be changed this this:

class UserController < ApplicationController
  def index
    respond_to |format|
      format.html { render "index" }
    end
  end
end

Alternatively to specifying the format, the following monkey patch can be applied in an initializer:

$ cat config/initializers/formats_filter.rb
# frozen_string_literal: true

ActionDispatch::Request.prepend(Module.new do
  def formats
    super().select do |format|
      format.symbol || format.ref == "*/*"
    end
  end
end)

Credits

Thanks to John Hawthorn john@hawthorn.email of GitHub

Description:

There is a potential Cross-Site Scripting (XSS) vulnerability in Action View's translation helpers. Views that allow the user to control the default (not found) value of the t and translate helpers could be susceptible to XSS attacks.

Impact

When an HTML-unsafe string is passed as the default for a missing translation key named html or ending in _html, the default string is incorrectly marked as HTML-safe and not escaped. Vulnerable code may look like the following examples:

<%# The welcome_html translation is not defined for the current locale: %>
<%= t("welcome_html", default: untrusted_user_controlled_string) %>

<%# Neither the title.html translation nor the missing.html translation is defined for the current locale: %>
<%= t("title.html", default: [:"missing.html", untrusted_user_controlled_string]) %>

Workarounds

Impacted users who can’t upgrade to a patched Rails version can avoid this issue by manually escaping default translations with the html_escape helper (aliased as h):

<%= t("welcome_html", default: h(untrusted_user_controlled_string)) %>

Description:

There is a possible XSS vulnerability in ActionView's JavaScript literal escape helpers. Views that use the j or escape_javascript methods may be susceptible to XSS attacks.

Versions Affected: All. Not affected: None. Fixed Versions: 6.0.2.2, 5.2.4.2

Impact

There is a possible XSS vulnerability in the j and escape_javascript methods in ActionView. These methods are used for escaping JavaScript string literals. Impacted code will look something like this:

<script>let a = `<%= j unknown_input %>`</script>

or

<script>let a = `<%= escape_javascript unknown_input %>`</script>

Releases

The 6.0.2.2 and 5.2.4.2 releases are available at the normal locations.

Workarounds

For those that can't upgrade, the following monkey patch may be used:

ActionView::Helpers::JavaScriptHelper::JS_ESCAPE_MAP.merge!(
  {
    "`" => "\\`",
    "$" => "\\$"
  }
)

module ActionView::Helpers::JavaScriptHelper
  alias :old_ej :escape_javascript
  alias :old_j :j

  def escape_javascript(javascript)
    javascript = javascript.to_s
    if javascript.empty?
      result = ""
    else
      result = javascript.gsub(/(\\|<\/|\r\n|\342\200\250|\342\200\251|[\n\r"']|[`]|[$])/u, JS_ESCAPE_MAP)
    end
    javascript.html_safe? ? result.html_safe : result
  end

  alias :j :escape_javascript
end

Description:

There was a vulnerability in versions of Rails prior to 5.0.1 that would allow an attacker who controlled the locals argument of a render call.

Versions Affected: rails < 5.0.1 Not affected: Applications that do not allow users to control the names of locals. Fixed Versions: 4.2.11.2

Impact

In the scenario where an attacker might be able to control the name of a local passed into render, they can acheive remote code execution.

Workarounds

Until such time as the patch can be applied, application developers should ensure that all user-provided local names are alphanumeric.

Description:

There is an vulnerability in rails-ujs that allows attackers to send CSRF tokens to wrong domains.

Versions Affected: rails <= 6.0.3 Not affected: Applications which don't use rails-ujs. Fixed Versions: rails >= 5.2.4.3, rails >= 6.0.3.1

Impact

This is a regression of CVE-2015-1840.

In the scenario where an attacker might be able to control the href attribute of an anchor tag or the action attribute of a form tag that will trigger a POST action, the attacker can set the href or action to a cross-origin URL, and the CSRF token will be sent.

Workarounds

To work around this problem, change code that allows users to control the href attribute of an anchor tag or the action attribute of a form tag to filter the user parameters.

For example, code like this:

link_to params

to code like this:

link_to filtered_params

def filtered_params
  # Filter just the parameters that you trust
end

Description:

There is a possible XSS vulnerability in Action View tag helpers. Passing untrusted input as hash keys can lead to a possible XSS vulnerability. This vulnerability has been assigned the CVE identifier CVE-2022-27777.

Versions Affected: ALL Not affected: NONE Fixed Versions: 7.0.2.4, 6.1.5.1, 6.0.4.8, 5.2.7.1

Impact

If untrusted data is passed as the hash key for tag attributes, there is a possibility that the untrusted data may not be properly escaped which can lead to an XSS vulnerability.

Impacted code will look something like this:

check_box_tag('thename', 'thevalue', false, aria: { malicious_input => 'thevalueofaria' })

Where the "malicious_input" variable contains untrusted data.

All users running an affected release should either upgrade or use one of the workarounds immediately.

Releases

The FIXED releases are available at the normal locations.

Workarounds

Escape the untrusted data before using it as a key for tag helper methods.

Description:

Impact

When a blank string is used as an HTML attribute name in Action View tag helpers, the attribute escaping is bypassed, producing malformed HTML. A carefully crafted attribute value could then be misinterpreted by the browser as a separate attribute name, possibly leading to XSS. Applications that allow users to specify custom HTML attributes are affected.

Releases

The fixed releases are available at the normal locations.

Description:

There is a vulnerability in Active Job. This vulnerability has been assigned the CVE identifier CVE-2018-16476.

Versions Affected: >= 4.2.0 Not affected: < 4.2.0 Fixed Versions: 4.2.11, 5.0.7.1, 5.1.6.1, 5.2.1.1

Impact

Carefully crafted user input can cause Active Job to deserialize it using GlobalId and allow an attacker to have access to information that they should not have.

Vulnerable code will look something like this:

MyJob.perform_later(user_input)

All users running an affected release should either upgrade or use one of the workarounds immediately.

Description:

There is a possible DoS vulnerability in the PostgreSQL adapter in Active Record. This vulnerability has been assigned the CVE identifier CVE-2021-22880.

Versions Affected: >= 4.2.0 Not affected: < 4.2.0 Fixed Versions: 6.1.2.1, 6.0.3.5, 5.2.4.5

Impact

Carefully crafted input can cause the input validation in the "money" type of the PostgreSQL adapter in Active Record to spend too much time in a regular expression, resulting in the potential for a DoS attack.

This only impacts Rails applications that are using PostgreSQL along with money type columns that take user input.

Workarounds

In the case a patch can't be applied, the following monkey patch can be used in an initializer:

module ActiveRecord
  module ConnectionAdapters
    module PostgreSQL
      module OID # :nodoc:
        class Money < Type::Decimal # :nodoc:
          def cast_value(value)
            return value unless ::String === value

            value = value.sub(/^\((.+)\)$/, '-\1') # (4)
            case value
            when /^-?\D*+[\d,]+\.\d{2}$/  # (1)
              value.gsub!(/[^-\d.]/, "")
            when /^-?\D*+[\d.]+,\d{2}$/  # (2)
              value.gsub!(/[^-\d,]/, "").sub!(/,/, ".")
            end

            super(value)
          end
        end
      end
    end
  end
end

Description:

There is a possible escalation to RCE when using YAML serialized columns in Active Record. This vulnerability has been assigned the CVE identifier CVE-2022-32224.

Versions Affected: All. Not affected: None Fixed Versions: 7.0.3.1, 6.1.6.1, 6.0.5.1, 5.2.8.1

Impact

When serialized columns that use YAML (the default) are deserialized, Rails uses YAML.unsafe_load to convert the YAML data in to Ruby objects. If an attacker can manipulate data in the database (via means like SQL injection), then it may be possible for the attacker to escalate to an RCE.

Impacted Active Record models will look something like this:

class User < ApplicationRecord
  serialize :options       # Vulnerable: Uses YAML for serialization
  serialize :values, Array # Vulnerable: Uses YAML for serialization
  serialize :values, JSON  # Not vulnerable
end

All users running an affected release should either upgrade or use one of the workarounds immediately.

Releases

The FIXED releases are available at the normal locations.

The released versions change the default YAML deserializer to use YAML.safe_load, which prevents deserialization of possibly dangerous objects. This may introduce backwards compatibility issues with existing data.

In order to cope with that situation, the released version also contains two new Active Record configuration options. The configuration options are as follows:

• config.active_record.use_yaml_unsafe_load

When set to true, this configuration option tells Rails to use the old "unsafe" YAML loading strategy, maintaining the existing behavior but leaving the possible escalation vulnerability in place. Setting this option to true is not recommended, but can aid in upgrading.

• config.active_record.yaml_column_permitted_classes

The "safe YAML" loading method does not allow all classes to be deserialized by default. This option allows you to specify classes deemed "safe" in your application. For example, if your application uses Symbol and Time in serialized data, you can add Symbol and Time to the allowed list as follows:

config.active_record.yaml_column_permitted_classes = [Symbol, Date, Time]

Workarounds

There are no feasible workarounds for this issue, but other coders (such as JSON) are not impacted.

Description:

There is a potential denial of service vulnerability present in ActiveRecord’s PostgreSQL adapter.

This has been assigned the CVE identifier CVE-2022-44566.

Versions Affected: All. Not affected: None. Fixed Versions: 6.1.7.1, 7.0.4.1

Impact

In ActiveRecord <7.0.4.1 and <6.1.7.1, when a value outside the range for a 64bit signed integer is provided to the PostgreSQL connection adapter, it will treat the target column type as numeric. Comparing integer values against numeric values can result in a slow sequential scan resulting in potential Denial of Service.

Workarounds

Ensure that user supplied input which is provided to ActiveRecord clauses do not contain integers wider than a signed 64bit representation or floats.

Description:

This vulnerability has been assigned the CVE identifier CVE-2025-55193

Impact

The ID passed to find or similar methods may be logged without escaping. If this is directly to the terminal, it may include unescaped ANSI sequences.

Releases

The fixed releases are available at the normal locations.

Credits

Thanks to lio346 for reporting this vulnerability.

Description:

There is potentially unexpected behaviour in the MemCacheStore and RedisCacheStore where, when untrusted user input is written to the cache store using the raw: true parameter, re-reading the result from the cache can evaluate the user input as a Marshalled object instead of plain text. Vulnerable code looks like:

data = cache.fetch("demo", raw: true) { untrusted_string }

Versions Affected: rails < 5.2.5, rails < 6.0.4 Not affected: Applications not using MemCacheStore or RedisCacheStore. Applications that do not use the raw option when storing untrusted user input. Fixed Versions: rails >= 5.2.4.3, rails >= 6.0.3.1

Impact

Unmarshalling of untrusted user input can have impact up to and including RCE. At a minimum, this vulnerability allows an attacker to inject untrusted Ruby objects into a web application.

In addition to upgrading to the latest versions of Rails, developers should ensure that whenever they are calling Rails.cache.fetch they are using consistent values of the raw parameter for both reading and writing, especially in the case of the RedisCacheStore which does not, prior to these changes, detect if data was serialized using the raw option upon deserialization.

Workarounds

It is recommended that application developers apply the suggested patch or upgrade to the latest release as soon as possible. If this is not possible, we recommend ensuring that all user-provided strings cached using the raw argument should be double-checked to ensure that they conform to the expected format.

Description:

There is a possible regular expression based DoS vulnerability in Active Support. This vulnerability has been assigned the CVE identifier CVE-2023-22796.

Versions Affected: All Not affected: None Fixed Versions: 6.1.7.1, 7.0.4.1

Impact

A specially crafted string passed to the underscore method can cause the regular expression engine to enter a state of catastrophic backtracking. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability.

This affects String#underscore, ActiveSupport::Inflector.underscore, String#titleize, and any other methods using these.

All users running an affected release should either upgrade or use one of the workarounds immediately.

Workarounds

There are no feasible workarounds for this issue.

Users on Ruby 3.2.0 or greater may be able to reduce the impact by configuring Regexp.timeout.

Description:

There is a vulnerability in ActiveSupport if the new bytesplice method is called on a SafeBuffer with untrusted user input. This vulnerability has been assigned the CVE identifier CVE-2023-28120.

Versions Affected: All. Not affected: None Fixed Versions: 7.0.4.3, 6.1.7.3

Impact

ActiveSupport uses the SafeBuffer string subclass to tag strings as htmlsafe after they have been sanitized. When these strings are mutated, the tag is should be removed to mark them as no longer being htmlsafe.

Ruby 3.2 introduced a new bytesplice method which ActiveSupport did not yet understand to be a mutation. Users on older versions of Ruby are likely unaffected.

All users running an affected release and using bytesplice should either upgrade or use one of the workarounds immediately.

Workarounds

Avoid calling bytesplice on a SafeBuffer (html_safe) string with untrusted user input.

Description:

Impact

NumberToDelimitedConverter used a regular expression with gsub! to insert thousands delimiters. This could produce quadratic time complexity on long digit strings.

Releases

The fixed releases are available at the normal locations.

Description:

Impact

SafeBuffer#% does not propagate the @html_unsafe flag to the newly created buffer. If a SafeBuffer is mutated in place (e.g. via gsub!) and then formatted with % using untrusted arguments, the result incorrectly reports html_safe? == true, bypassing ERB auto-escaping and possibly leading to XSS.

Releases

The fixed releases are available at the normal locations.

Description:

Impact

Active Support number helpers accept strings containing scientific notation (e.g. 1e10000), which when converted to a string could be expanded into extremely large decimal representations. This can cause excessive memory allocation and CPU consumption when the expanded number is formatted, possibly resulting in a DoS vulnerability.

Releases

The fixed releases are available at the normal locations.

Description:

Within the URI template implementation in Addressable, a maliciously crafted template may result in uncontrolled resource consumption, leading to denial of service when matched against a URI. In typical usage, templates would not normally be read from untrusted user input, but nonetheless, no previous security advisory for Addressable has cautioned against doing this. Users of the parsing capabilities in Addressable but not the URI template capabilities are unaffected.

Description:

Impact

Within the URI template implementation in Addressable, two classes of URI template generate regular expressions vulnerable to catastrophic backtracking:

1. Templates using the * (explode) modifier with any expansion operator (e.g., {foo*}, {+var*}, {#var*}, {/var*}, {.var*}, {;var*}, {?var*}, {&var*}) generate patterns with nested unbounded quantifiers that are O(2^n) when matched against a maliciously crafted URI.

2. Templates using multiple variables with the + or # operators (e.g., {+v1,v2,v3}) generate patterns with O(n^k) complexity due to the comma separator being within the matched character class, causing ambiguous backtracking across k variables.

When matched against a maliciously crafted URI, this can result in catastrophic backtracking and uncontrolled resource consumption, leading to denial of service. The first pattern was partially addressed in 2.8.10 for certain operator combinations. Both patterns are fully remediated in 2.9.0.

Users of the URI parsing capabilities in Addressable but not the URI template matching capabilities are unaffected.

Affected Versions

This vulnerability affects Addressable >= 2.3.0 (note: 2.3.0 and 2.3.1 were yanked; the earliest installable release is 2.3.2). It was partially fixed in version 2.8.10 and fully remediated in 2.9.0.

The vulnerability is more exploitable on MRI Ruby < 3.2 and on all versions of JRuby and TruffleRuby. MRI Ruby 3.2 and later ship with Onigmo 6.9, which introduces memoization that prevents catastrophic backtracking for the first class of template. JRuby and TruffleRuby do not implement equivalent memoization and remain vulnerable to all patterns.

This has been confirmed on the following runtimes:

| Runtime | Status | |--------------|--------| | MRI Ruby 2.6 | Vulnerable | | MRI Ruby 2.7 | Vulnerable | | MRI Ruby 3.0 | Vulnerable | | MRI Ruby 3.1 | Vulnerable | | MRI Ruby 3.2 | Partially vulnerable | | MRI Ruby 3.3 | Partially vulnerable | | MRI Ruby 3.4 | Partially vulnerable | | MRI Ruby 4.0 | Partially vulnerable | | JRuby 10.0 | Vulnerable | | TruffleRuby 21.2 | Vulnerable |

Workarounds

• Upgrade to MRI Ruby 3.2 or later, if your application does not use JRuby or TruffleRuby. The Onigmo memoization introduced in MRI Ruby 3.2 prevents catastrophic backtracking from nested unbounded quantifiers (pattern 1 above — templates using the * modifier). It does not reliably mitigate the O(n^k) multi-variable case (pattern 2), so upgrading Ruby alone may not be sufficient if your templates use {+v1,v2,...} or {#v1,v2,...} syntax.

• Avoid using vulnerable template patterns when matching user-supplied input on unpatched versions of the library:

  • Templates using the * (explode) modifier: {foo*}, {+var*}, {#var*}, {.var*}, {/var*}, {;var*}, {?var*}, {&var*}
  • Templates using multiple variables with the + or # operators: {+v1,v2}, {#v1,v2,v3}, etc.

• Apply a short timeout around any call to Template#match or Template#extract that processes user-supplied data.

Credits

Discovered in collaboration with @jamfish.

For more information

If you have any questions or comments about this advisory: * Open an issue

Description:

Impact

An integer overflow in the Java BCrypt implementation for JRuby can cause zero iterations in the strengthening loop. Impacted applications must be setting the cost to 31 to see this happen.

The JRuby implementation of bcrypt-ruby (BCrypt.java) computes the key-strengthening round count as a signed 32-bit integer. When cost=31 (the maximum allowed by the gem), signed integer overflow causes the round count to become negative, and the strengthening loop executes zero iterations. This collapses bcrypt from 2^31 rounds of exponential key-strengthening to effectively constant-time computation — only the initial EksBlowfish key setup and final 64x encryption phase remain.

The resulting hash looks valid ($2a$31$...) and verifies correctly via checkpw, making the weakness invisible to the application. This issue is triggered only when cost=31 is used or when verifying a $2a$31$ hash.

Patches

This problem has been fixed in version 3.1.22

Workarounds

Set the cost to something less than 31.

Description:

In Bootstrap 3.x before 3.4.0 and 4.x-beta before 4.0.0-beta.2, XSS is possible in the data-target attribute.

Description:

In Bootstrap starting in version 2.3.0 and prior to 3.4.0, as well as 4.x before 4.1.2, XSS is possible in the collapse data-parent attribute.

Description:

In Bootstrap starting in version 2.3.0 and prior to versions 3.4.0 and 4.1.2, XSS is possible in the data-container property of tooltip. This is similar to CVE-2018-14041.

Description:

In Bootstrap before 3.4.0, XSS is possible in the tooltip data-viewport attribute.

Description:

In Bootstrap before 3.4.0, XSS is possible in the affix configuration target property.

Description:

In Bootstrap before 3.4.1 and 4.3.x before 4.3.1, XSS is possible in the tooltip or popover data-template attribute.

Description:

Impact

[CarrierWave download feature](https://github.com/carrierwaveuploader/carrierwave#uploading-files-from-a-remote-location has an SSRF vulnerability, allowing attacks to provide DNS entries or IP addresses that are intended for internal use and gather information about the Intranet infrastructure of the platform.

Patches

Upgrade to 2.1.1 or 1.3.2.

Workarounds

Using proper network segmentation and applying the principle of least privilege to outbound connections from application servers can reduce the severity of SSRF vulnerabilities. Ideally the vulnerable gem should run on an isolated server without access to any internal network resources or cloud metadata access.

Description:

Impact

CarrierWave::RMagick has a Code Injection vulnerability. Its #manipulate! method inappropriately evals the content of mutation option(:read/:write), allowing attackers to craft a string that can be executed as a Ruby code. If an application developer supplies untrusted inputs to the option, it will lead to remote code execution(RCE).

(But supplying untrusted input to the option itself is dangerous even in absence of this vulnerability, since is prone to DoS vulnerability - attackers can try to consume massive amounts of memory by resizing to a very large dimension)

Patches

Upgrade to 2.1.1 or 1.3.2.

Workarounds

Stop supplying untrusted input to #manipulate!'s mutation option.

Description:

Impact

CarrierWave::Uploader::ContentTypeAllowlist has a Content-Type allowlist bypass vulnerability, possibly leading to XSS.

The validation in allowlisted_content_type? determines Content-Type permissions by performing a partial match. If the content_type argument of allowlisted_content_type? is passed a value crafted by the attacker, Content-Types not included in the content_type_allowlist will be allowed.

In addition, by setting the Content-Type configured by the attacker at the time of file delivery, it is possible to cause XSS on the user's browser when the uploaded file is opened.

Patches

Upgrade to 3.0.5 or 2.2.5.

Workarounds

When validating with allowlisted_content_type? in CarrierWave::Uploader::ContentTypeAllowlist, forward match(\\A) the Content-Type set in content_type_allowlist, preventing unintentional permission of text/html;image/png when you want to allow only image/png in content_type_allowlist.

References

OWASP - File Upload Cheat Sheet

Description:

Impact

The vulnerability CVE-2023-49090 wasn't fully addressed.

This vulnerability is caused by the fact that when uploading to object storage, including Amazon S3, it is possible to set a Content-Type value that is interpreted by browsers to be different from what's allowed by content_type_allowlist, by providing multiple values separated by commas.

This bypassed value can be used to cause XSS.

Patches

Upgrade to 3.0.7 or 2.2.6.

Workarounds

Use the following monkey patch to let CarrierWave parse the Content-type by using Marcel::MimeType.for.

# For CarrierWave 3.x
CarrierWave::SanitizedFile.class_eval do
  def declared_content_type
    @declared_content_type ||
      if @file.respond_to?(:content_type) && @file.content_type
        Marcel::MimeType.for(declared_type: @file.content_type.to_s.chomp)
      end
  end
end

# For CarrierWave 2.x
CarrierWave::SanitizedFile.class_eval do
  def existing_content_type
    if @file.respond_to?(:content_type) && @file.content_type
      Marcel::MimeType.for(declared_type: @file.content_type.to_s.chomp)
    end
  end
end

References

OWASP - File Upload Cheat Sheet

Description:

Summary

CarrierWave's contenttypedenylist check fails to escape regex metacharacters in string entries, causing the denylist to silently not match the content types it is intended to block.

Note: CarrierWave is aware #content_type_denylist is deprecated for the security reason, but it still used by developers, and the problem here isn't denylist allows any filetype, and thats not a vulnerability in carrierwave, its an implementation problem in developers using CarrierWave, the problem is its denylist entries are interpolated directly into a regex without Regexp.quote or anchoring. The denylist is still useful when developers want to ban specific content types but allow everything else.

Details

In lib/carrierwave/uploader/content_type_denylist.rb:57, string denylist entries are interpolated directly into a regex without Regexp.quote or anchoring:

def denylisted_content_type?(denylist, content_type)
  Array(denylist).any? { |item| content_type =~ /#{item}/ }
end

The entry "image/svg+xml" becomes the regex /image\/svg+xml/ where +
is a quantifier meaning "one or more g", not a literal +. This
regex never matches the real MIME type "image/svg+xml" which contains
a literal +. This is inconsistent with the allowlist implementation
at lib/carrierwave/uploader/content_type_allowlist.rb:53-57, which
correctly applies both Regexp.quote and a \A anchor:

rubydef allowlisted_content_type?(allowlist, content_type)
  Array(allowlist).any? do |item|
    item = Regexp.quote(item) if item.class != Regexp
    content_type =~ /\A#{item}/
  end
end

Other affected MIME types include application/xhtml+xml and any type containing regex metacharacters.

Fix: Apply Regexp.quote for string entries and anchor with \A, matching the existing allowlist implementation:

rubydef denylisted_content_type?(denylist, content_type)
  Array(denylist).any? do |item|
    item = Regexp.quote(item) if item.class != Regexp
    content_type =~ /\A#{item}/
  end
end

Impact

Any application that uses contenttypedenylist to block image/svg+xml — the most common use case, specifically to prevent stored XSS — is silently unprotected.

Description:

Summary

Concurrent::AtomicReference#update can enter a permanent busy retry loop when the current value is Float::NAN.

The issue is caused by the interaction between: - AtomicReference#update, which retries until compare_and_set(old_value, new_value) succeeds. - Numeric compare_and_set, which checks old == old_value before attempting the underlying atomic swap. - Ruby NaN semantics, where Float::NAN == Float::NAN is always false.

As a result, once an AtomicReference contains Float::NAN, calling #update repeatedly evaluates the caller's block and never returns. In services that store externally derived numeric values in an AtomicReference, this can cause CPU exhaustion or permanent request/job hangs.

Impact

This is an application-level denial of service issue. If an application stores externally derived numeric data in a Concurrent::AtomicReference, an attacker or faulty upstream data source may be able to cause the stored value to become Float::NAN. Any later call to AtomicReference#update on that reference will spin indefinitely, repeatedly executing the update block and consuming CPU.

Credit

Pranjali Thakur - depthfirst (depthfirst.com)

Description:

Summary

Concurrent::ReentrantReadWriteLock can incorrectly grant a write lock after one thread acquires the read lock 32,768 times.

The lock stores a thread's local read and write hold counts in one integer. The low 15 bits are used for the read hold count, and bit 15 is used as WRITE_LOCK_HELD. After 32,768 reentrant read acquisitions, the local read count crosses into the write-lock bit. try_write_lock then treats the thread as already holding a write lock and returns true without setting the global RUNNING_WRITER bit.

This breaks the core mutual-exclusion guarantee: the caller is told it has a write lock, but other threads can still hold or acquire read locks at the same time.

Impact

This breaks the write-lock exclusivity guarantee. After the overflow, a thread can be told it has acquired the write lock while other threads can still hold or acquire read locks, allowing races and inconsistent reads of protected mutable state.

Credit

Pranjali Thakur - depthfirst (depthfirst.com)

Description:

Summary

Concurrent::ReadWriteLock#release_write_lock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can then enter its critical section while the first writer is still running.

Concurrent::ReadWriteLock#release_read_lock also decrements the shared counter even when no read lock is held. Calling it on a fresh lock changes the counter from 0 to -1, after which normal read acquisition raises Concurrent::ResourceLimitError.

This is a synchronization correctness issue in the public Concurrent::ReadWriteLock API. It should not be framed as an authorization bypass; the lock is an in-process concurrency primitive, not an access-control boundary.

Impact

This can break the write-lock mutual exclusion guarantee and can also leave a lock unusable after a stray read release. The impact is local to applications that expose or misuse the manual acquire_* / release_* APIs. If the lock protects integrity-sensitive mutable state, wrong-thread write release can allow concurrent writers and data races. The stray read-release path can cause denial of service by corrupting the lock counter.

Credit

Pranjali Thakur - depthfirst (depthfirst.com)

Description:

Impact

Crass recursively parses CSS simple blocks and functions without a depth guard. An attacker-controlled value containing many deeply nested blocks can recurse until Ruby raises SystemStackError: stack level too deep, or can cause excessive memory usage.

Description:

Impact

Crass converts CSS scientific notation number values with unbounded exponentiation before it clamps the result to Float::MAX. Applications that use Crass to parse attacker-controlled CSS strings can be forced to spend disproportionate CPU and memory parsing a tiny input, possibly resulting in a crash.

Exponents are now bounded before 10**exponent is computed.

Description:

Impact

When parsing an input containing non-ASCII characters, inefficiencies in how Crass tracks the positions of multi-byte characters result in superlinear parsing time. An attacker-controlled input consisting of many non-ASCII characters could cause excessive CPU consumption and potentially denial of service.

Description:

Summary

Crass's tokenizer didn't terminate a bad URL token at a ) that followed an escaped backslash (\). As a result, Crass consumed more input as part of the bad URL than a spec-compliant browser does. CSS sanitizers that parse untrusted CSS with Crass and re-emit it could be tricked into passing through declarations, style rules, or at-rules (including @import) that the sanitizer would otherwise have removed, but that a browser would then parse and apply.

Impact

Crass by itself only mis-tokenizes input. The security impact is on CSS sanitizers that use Crass to make allow/deny decisions and then re-serialize the CSS. Exploitation requires a sanitizer that doesn't reject bad URL tokens wherever they occur. Confirmed examples:

• Sanitize (all versions through 7.0.0): Sanitize::CSS.properties, style attributes, Sanitize::CSS.stylesheet, and