Package Instance

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.

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.

Improper neutralization of data URIs may allow XSS in rails-html-sanitizer
## Summary

rails-html-sanitizer `>= 1.0.3, < 1.4.4` is vulnerable to cross-site scripting via data URIs when used in combination with Loofah `>= 2.1.0`.


## Mitigation

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


## Severity

The maintainers have evaluated this as [Medium Severity 6.1](https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).


## 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)
- [SVG MIME Type (image/svg+xml) is misleading to developers · Issue #266 · w3c/svgwg](https://github.com/w3c/svgwg/issues/266)
- https://github.com/rails/rails-html-sanitizer/issues/135
- https://hackerone.com/reports/1694173


## Credit

This vulnerability was independently reported by Maciej Piechota (@haqpl) and Mrinmoy Das (@goromlagche).

XSS vulnerability
The gem allows attributes that are not specified in the allowlist to be present in sanitized output when input with specially-crafted HTML fragments, and these attributes can lead to an XSS attack on target applications. This issue is similar to CVE-2018-8048 in Loofah.

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

There is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer. This is due to an incomplete fix of CVE-2022-32209.

- 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 to allow both "select" and "style" elements.

Code is only impacted if allowed tags are being overridden using either of the following two mechanisms:

1. Using the Rails configuration `config.action_view.sanitized_allow_tags=`:

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

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

2. Using the class method `Rails::Html::SafeListSanitizer.allowed_tags=`:

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

All users overriding the allowed tags by either of the above mechanisms to include both "select" and "style" should either upgrade or use one of the workarounds immediately.

NOTE: Code is _not_ impacted if allowed tags are overridden using either of the following mechanisms:

- the `:tags` option to the Action View helper method `sanitize`.
- the `:tags` option to the instance method `SafeListSanitizer#sanitize`.


## Workarounds

Remove either "select" or "style" 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://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-32209
- https://hackerone.com/reports/1654310


## Credit

This vulnerability was responsibly reported by Dominic Breuker.