Moderate severity vulnerability that affects actionview

Withdrawn, accidental duplicate publish.

Directory traversal vulnerability in Action View in Ruby on Rails before 3.2.22.2 and 4.x before 4.1.14.2 allows remote attackers to read arbitrary files by leveraging an application's unrestricted use of the render method and providing a .. (dot dot) in a pathname. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-0752.

Cross site scripting vulnerability in ActionView

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

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

Patches

To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.

• 5-2-js-helper-xss.patch - Patch for 5.2 series
• 6-0-js-helper-xss.patch - Patch for 6.0 series

Please note that only the 5.2 and 6.0 series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.

Credits

Thanks to Jesse Campos from Chef Secure

Path Traversal in Action View

File Content Disclosure in Action View

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

XSS in Action View

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]) %>

Patches

Patched Rails versions, 6.0.3.3 and 5.2.4.4, are available from the normal locations.

The patches have also been applied to the master, 6-0-stable, and 5-2-stable branches on GitHub. If you track any of these branches, you should update to the latest.

To aid users who aren’t able to upgrade immediately, we’ve provided patches for the two supported release series. They are in git-am format and consist of a single changeset.

• 5-2-translate-helper-xss.patch — patch for the 5.2 release series
• 6-0-translate-helper-xss.patch — patch for the 6.0 release series

Please note that only the 5.2 and 6.0 release series are currently supported. Users of earlier, unsupported releases are advised to update as soon as possible, as we cannot provide security fixes for unsupported releases.

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)) %>

XSS Vulnerability in Action View tag helpers

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.

Remote code execution via user-provided local names in ActionView

The is a code injection vulnerability in versions of Rails prior to 5.0.1 that would allow an attacker who controlled the locals argument of a render call to perform a RCE.

Denial of Service Vulnerability in Action View

Denial of Service Vulnerability in Action View

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.

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 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) 

Please note that only the 5.2.x, 5.1.x, 5.0.x, and 4.2.x series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.

Also note that the patches for this vulnerability are the same as CVE-2019-5418.

Credits

Thanks to John Hawthorn john@hawthorn.email of GitHub

actionview Cross-site Scripting vulnerability

Cross-site scripting (XSS) vulnerability in Action View in Ruby on Rails 3.x before 3.2.22.3, 4.x before 4.2.7.1, and 5.x before 5.0.0.1 might allow remote attackers to inject arbitrary web script or HTML via text declared as HTML safe and used as attribute values in tag handlers.

actionview contains Path Traversal vulnerability

There is a possible directory traversal and information leak vulnerability in Action View. This was meant to be fixed on CVE-2016-0752. However the 3.2 patch was not covering all possible scenarios. This vulnerability has been assigned the CVE identifier CVE-2016-2097.

Versions Affected: 3.2.x, 4.0.x, 4.1.x Not affected: 4.2+ Fixed Versions: 3.2.22.2, 4.1.14.2

Impact

Applications that pass unverified user input to the render method in a controller may be vulnerable to an information leak vulnerability.

Impacted code will look something like this:

def index
  render params[:id]
end

Carefully crafted requests can cause the above code to render files from unexpected places like outside the application's view directory, and can possibly escalate this to a remote code execution attack.

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

A workaround to this issue is to not pass arbitrary user input to the render method. Instead, verify that data before passing it to the render method.

For example, change this:

def index
  render params[:id]
end

To this:

def index
  render verify_template(params[:id])
end

private
def verify_template(name)
  # add verification logic particular to your application here
end

Patches

To aid users who aren't able to upgrade immediately we have provided patches for it. It is in git-am format and consist of a single changeset.

• 3-2-renderdataleak_2.patch - Patch for 3.2 series
• 4-1-renderdataleak_2.patch - Patch for 4.1 series

Credits

Thanks to both Jyoti Singh and Tobias Kraze from makandra for reporting this and working with us in the patch!

Directory traversal vulnerability in Action View in Ruby on Rails

Directory traversal vulnerability in Action View in Ruby on Rails before 3.2.22.1, 4.0.x and 4.1.x before 4.1.14.1, 4.2.x before 4.2.5.1, and 5.x before 5.0.0.beta1.1 allows remote attackers to read arbitrary files by leveraging an application's unrestricted use of the render method and providing a .. (dot dot) in a pathname.

Possible Information Leak Vulnerability in Action View

There is a possible directory traversal and information leak vulnerability in Action View. This vulnerability has been assigned the CVE identifier CVE-2016-0752.

Versions Affected: All. Not affected: None. Fixed Versions: 5.0.0.beta1.1, 4.2.5.1, 4.1.14.1, 3.2.22.1

Impact

Applications that pass unverified user input to the render method in a controller may be vulnerable to an information leak vulnerability.

Impacted code will look something like this:

def index
  render params[:id]
end

Carefully crafted requests can cause the above code to render files from unexpected places like outside the application's view directory, and can possibly escalate this to a remote code execution attack.

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

A workaround to this issue is to not pass arbitrary user input to the render method. Instead, verify that data before passing it to the render method.

For example, change this:

def index
  render params[:id]
end

To this:

def index
  render verify_template(params[:id])
end

private
def verify_template(name)
  # add verification logic particular to your application here
end

Patches

To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.

• 3-2-renderdataleak.patch - Patch for 3.2 series
• 4-1-renderdataleak.patch - Patch for 4.1 series
• 4-2-renderdataleak.patch - Patch for 4.2 series
• 5-0-renderdataleak.patch - Patch for 5.0 series

Please note that only the 4.1.x and 4.2.x series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.

Credits

Thanks John Poulin for reporting this!

Possible Information Leak Vulnerability in Action View

There is a possible directory traversal and information leak vulnerability in Action View. This was meant to be fixed on CVE-2016-0752. However the 3.2 patch was not covering all the scenarios. This vulnerability has been assigned the CVE identifier CVE-2016-2097.

Versions Affected: 3.2.x, 4.0.x, 4.1.x Not affected: 4.2+ Fixed Versions: 3.2.22.2, 4.1.14.2

Impact

Applications that pass unverified user input to the render method in a controller may be vulnerable to an information leak vulnerability.

Impacted code will look something like this:

def index
  render params[:id]
end

Carefully crafted requests can cause the above code to render files from unexpected places like outside the application's view directory, and can possibly escalate this to a remote code execution attack.

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

A workaround to this issue is to not pass arbitrary user input to the render method. Instead, verify that data before passing it to the render method.

For example, change this:

def index
  render params[:id]
end

To this:

def index
  render verify_template(params[:id])
end

private
def verify_template(name)
  # add verification logic particular to your application here
end

Patches

To aid users who aren't able to upgrade immediately we have provided patches for it. It is in git-am format and consist of a single changeset.

• 3-2-renderdataleak_2.patch - Patch for 3.2 series
• 4-1-renderdataleak_2.patch - Patch for 4.1 series

Credits

Thanks to both Jyoti Singh and Tobias Kraze from makandra for reporting this and working with us in the patch!

Possible XSS Vulnerability in Action View

There is a possible XSS vulnerability in Action View. Text declared as HTML safe will not have quotes escaped when used as attribute values in tag helpers.

Impact

Text declared as HTML safe when passed as an attribute value to a tag helper will not have quotes escaped which can lead to an XSS attack. Impacted code looks something like this:

content_tag(:div, "hi", title: user_input.html_safe)

Some helpers like the sanitize helper will automatically mark strings as HTML safe, so impacted code could also look something like this:

content_tag(:div, "hi", title: sanitize(user_input))

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

Workarounds

You can work around this issue by either not marking arbitrary user input as safe, or by manually escaping quotes like this:

def escape_quotes(value)
  value.gsub(/"/, '"'.freeze)
end

content_tag(:div, "hi", title: escape_quotes(sanitize(user_input)))

File Content Disclosure in Action View

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

Denial of Service Vulnerability in Action View

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

Potential XSS vulnerability in Action View

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)) %>

Possible XSS vulnerability in ActionView

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

Potential remote code execution of user-provided local names in ActionView

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.

CSRF Vulnerability in rails-ujs

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

Possible XSS Vulnerability in Action View tag helpers

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.