Package Instance

XSS vulnerability - white list bypass
Carefully crafted strings can cause user input to bypass the sanitization in the white list sanitizer which can lead to an XSS attack.

Moderate severity vulnerability that affects rails-html-sanitizer
Withdrawn, accidental duplicate publish.

Cross-site scripting (XSS) vulnerability in the rails-html-sanitizer gem before 1.0.3 for Ruby on Rails 4.2.x and 5.x allows remote attackers to inject arbitrary web script or HTML via crafted tag attributes.

Moderate severity vulnerability that affects rails-html-sanitizer
Withdrawn, accidental duplicate publish.

Cross-site scripting (XSS) vulnerability in lib/rails/html/scrubbers.rb in the rails-html-sanitizer gem before 1.0.3 for Ruby on Rails 4.2.x and 5.x allows remote attackers to inject arbitrary web script or HTML via a crafted CDATA node.

Inefficient Regular Expression Complexity in rails-html-sanitizer
## Summary

Certain configurations of rails-html-sanitizer `< 1.4.4` use an inefficient regular expression that is susceptible to excessive backtracking when attempting to sanitize certain SVG attributes. This may lead to a denial of service through CPU resource consumption.


## Mitigation

Upgrade to rails-html-sanitizer `>= 1.4.4`.


## Severity

The maintainers have evaluated this as [High Severity 7.5 (CVSS3.1)](https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).


## References

- [CWE - CWE-1333: Inefficient Regular Expression Complexity (4.9)](https://cwe.mitre.org/data/definitions/1333.html)
- https://hackerone.com/reports/1684163


## Credit

This vulnerability was responsibly reported by @ooooooo-q (https://github.com/ooooooo-q).

Possible XSS vulnerability with certain configurations of rails-html-sanitizer
## Summary

There is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer.

- Versions affected: ALL
- Not affected: NONE
- Fixed versions: 1.4.4


## Impact

A possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer may allow an attacker to inject content if the application developer has overridden the sanitizer's allowed tags in either of the following ways:

- allow both "math" and "style" elements,
- or allow both "svg" and "style" elements

Code is only impacted if allowed tags are being overridden. Applications may be doing this in four different ways:

1. using application configuration:

  ```ruby
  # In config/application.rb
  config.action_view.sanitized_allowed_tags = ["math", "style"]
  # or
  config.action_view.sanitized_allowed_tags = ["svg", "style"]
  ```

  see https://guides.rubyonrails.org/configuring.html#configuring-action-view

2. using a `:tags` option to the Action View helper `sanitize`:

  ```
  <%= sanitize @comment.body, tags: ["math", "style"] %>
  <%# or %>
  <%= sanitize @comment.body, tags: ["svg", "style"] %>
  ```

  see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize

3. using Rails::Html::SafeListSanitizer class method `allowed_tags=`:

  ```ruby
  # class-level option
  Rails::Html::SafeListSanitizer.allowed_tags = ["math", "style"]
  # or
  Rails::Html::SafeListSanitizer.allowed_tags = ["svg", "style"]
  ```

4. using a `:tags` options to the Rails::Html::SafeListSanitizer instance method `sanitize`:

  ```ruby
  # instance-level option
  Rails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: ["math", "style"])
  # or
  Rails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: ["svg", "style"])
  ```

All users overriding the allowed tags by any of the above mechanisms to include (("math" or "svg") and "style") should either upgrade or use one of the workarounds immediately.


## Workarounds

Remove "style" from the overridden allowed tags, or remove "math" and "svg" from the overridden allowed tags.


## References

- [CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9)](https://cwe.mitre.org/data/definitions/79.html)
- https://hackerone.com/reports/1656627


## Credit

This vulnerability was responsibly reported by Dominic Breuker.

Moderate severity vulnerability that affects rails-html-sanitizer
Withdrawn, accidental duplicate publish.

Cross-site scripting (XSS) vulnerability in the rails-html-sanitizer gem 1.0.2 for Ruby on Rails 4.2.x and 5.x allows remote attackers to inject arbitrary web script or HTML via an HTML entity that is mishandled by the Rails::Html::FullSanitizer class.

rails-html-sanitizer has XSS vulnerability with certain configurations
## Summary

There is a possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer 1.6.0 when used with Rails >= 7.1.0.

* Versions affected: 1.6.0
* Not affected: < 1.6.0
* Fixed versions: 1.6.1

## Impact

A possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer may allow an attacker to inject content if HTML5 sanitization is enabled and the application developer has overridden the sanitizer's allowed tags in the following way:

- the "noscript" element is explicitly allowed

Code is only impacted if Rails is configured to use HTML5 sanitization, please see documentation for [`config.action_view.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-view-sanitizer-vendor) and [`config.action_text.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-text-sanitizer-vendor) for more information on these configuration options.

The default configuration is to disallow all of these elements. Code is only impacted if allowed tags are being overridden. Applications may be doing this in a few different ways:

1. using application configuration to configure Action View sanitizers' allowed tags:

  ```ruby
  # In config/application.rb
  config.action_view.sanitized_allowed_tags = ["noscript"]
  ```

  see https://guides.rubyonrails.org/configuring.html#configuring-action-view

2. using a `:tags` option to the Action View helper `sanitize`:

  ```
  <%= sanitize @comment.body, tags: ["noscript"] %>
  ```

  see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize

3. setting Rails::HTML5::SafeListSanitizer class attribute `allowed_tags`:

  ```ruby
  # class-level option
  Rails::HTML5::SafeListSanitizer.allowed_tags = ["noscript"]
  ```

  (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`)

4. using a `:tags` options to the Rails::HTML5::SafeListSanitizer instance method `sanitize`:

  ```ruby
  # instance-level option
  Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: ["noscript"])
  ```

  (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`)

5. setting ActionText::ContentHelper module attribute `allowed_tags`:

  ```ruby
  ActionText::ContentHelper.allowed_tags = ["noscript"]
  ```

All users overriding the allowed tags by any of the above mechanisms to include "noscript" should either upgrade or use one of the workarounds.


## Workarounds

Any one of the following actions will work around this issue:

- Remove "noscript" from the overridden allowed tags,
- Or, downgrade sanitization to HTML4 (see documentation for [`config.action_view.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-view-sanitizer-vendor) and [`config.action_text.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-text-sanitizer-vendor) for more information).


## References

- [CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9)](https://cwe.mitre.org/data/definitions/79.html)
- Original report: https://hackerone.com/reports/2509647

## Credit

This vulnerability was responsibly reported by So Sakaguchi ([mokusou](https://hackerone.com/mokusou)) and [taise](https://hackerone.com/taise).

rails-html-sanitize has XSS vulnerability with certain configurations
## Summary

There is a possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer 1.6.0 when used with Rails >= 7.1.0 and Nokogiri < 1.15.7, or 1.16.x < 1.16.8.

* Versions affected: 1.6.0
* Not affected: < 1.6.0
* Fixed versions: 1.6.1

Please note that the fix in v1.6.1 is to update the dependency on Nokogiri to 1.15.7 or >= 1.16.8.


## Impact

A possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer may allow an attacker to inject content if HTML5 sanitization is enabled and the application developer has overridden the sanitizer's allowed tags in either of the following ways:

* allow both "math" and "style" elements
* or allow both "svg" and "style" elements

Code is only impacted if Rails is configured to use HTML5 sanitization, please see documentation for [`config.action_view.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-view-sanitizer-vendor) and [`config.action_text.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-text-sanitizer-vendor) for more information on these configuration options.

Code is only impacted if allowed tags are being overridden. Applications may be doing this in a few different ways:

1. using application configuration to configure Action View sanitizers' allowed tags:

  ```ruby
  # In config/application.rb
  config.action_view.sanitized_allowed_tags = ["math", "style"]
  # or
  config.action_view.sanitized_allowed_tags = ["svg", "style"]
  ```

  see https://guides.rubyonrails.org/configuring.html#configuring-action-view

2. using a `:tags` option to the Action View helper `sanitize`:

  ```
  <%= sanitize @comment.body, tags: ["math", "style"] %>
  <%# or %>
  <%= sanitize @comment.body, tags: ["svg", "style"] %>
  ```

  see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize

3. setting Rails::HTML5::SafeListSanitizer class attribute `allowed_tags`:

  ```ruby
  # class-level option
  Rails::HTML5::SafeListSanitizer.allowed_tags = ["math", "style"]
  # or
  Rails::HTML5::SafeListSanitizer.allowed_tags = ["svg", "style"]
  ```

  (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`)

4. using a `:tags` options to the Rails::HTML5::SafeListSanitizer instance method `sanitize`:

  ```ruby
  # instance-level option
  Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: ["math", "style"])
  # or
  Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: ["svg", "style"])
  ```

  (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`)

5. setting ActionText::ContentHelper module attribute `allowed_tags`:

  ```ruby
  ActionText::ContentHelper.allowed_tags = ["math", "style"]
  # or
  ActionText::ContentHelper.allowed_tags = ["svg", "style"]
  ```

All users overriding the allowed tags by any of the above mechanisms to include (("math" or "svg") and "style") should either upgrade or use one of the workarounds.


## Workarounds

Any one of the following actions will work around this issue:

- Remove "style" from the overridden allowed tags,
- Or, remove "math" and "svg" from the overridden allowed tags,
- Or, downgrade sanitization to HTML4 (see documentation for [`config.action_view.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-view-sanitizer-vendor) and [`config.action_text.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-text-sanitizer-vendor) for more information)
- Or, independently upgrade Nokogiri to v1.15.7 or >= 1.16.8.


## References

- [CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9)](https://cwe.mitre.org/data/definitions/79.html)
- Original report: https://hackerone.com/reports/2503220


## Credit

This vulnerability was responsibly reported by So Sakaguchi ([mokusou](https://hackerone.com/mokusou)) and [taise](https://hackerone.com/taise).

Rails::Html::Sanitizer vulnerable to Cross-site Scripting
Versions of Rails::Html::Sanitizer prior to version 1.4.3 are vulnerable to XSS with certain configurations of Rails::Html::Sanitizer which  allows an attacker to inject content when the application developer has overridden the sanitizer's allowed tags to allow both `select` and `style` elements. Code is only impacted if allowed tags are being overridden. 

This may be done via application configuration: ```ruby# In config/application.rbconfig.action_view.sanitized_allowed_tags = ["select", "style"]```

see https://guides.rubyonrails.org/configuring.html#configuring-action-view

Or it may be done with a `:tags` option to the Action View helper `sanitize`: ```<%= sanitize @comment.body, tags: ["select", "style"] %>``` 

see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize 

It may also be done with Rails::Html::SafeListSanitizer directly: 
```ruby# class-level optionRails::Html::SafeListSanitizer.allowed_tags = ["select", "style"]```  or with
```ruby# instance-level optionRails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: ["select", "style"])```

All users overriding the allowed tags by any of the above mechanisms to include both "select" and "style" are recommended to upgrade immediately. A workaround for this issue can be applied by removing either `select` or `style` from the overridden allowed tags.

Possible XSS vulnerability
Certain attributes are not removed from tags when they are sanitized, and these attributes can lead to an XSS attack on target applications.