Package Instance

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`](https://guides.rubyonrails.org/i18n.html#using-safe-html-translations), the default string is incorrectly marked as HTML-safe and not escaped. Vulnerable code may look like the following examples:

```erb
<%# 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](https://gist.github.com/georgeclaghorn/a466e103922ee81f24c32c9034089442#file-5-2-translate-helper-xss-patch) — patch for the 5.2 release series
* [6-0-translate-helper-xss.patch](https://gist.github.com/georgeclaghorn/a466e103922ee81f24c32c9034089442#file-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`):

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

Possible XSS Vulnerability in ActionView
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.

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: 

``` ruby
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: 

``` ruby
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: 

``` ruby
$ 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

Allocation of Resources Without Limits or Throttling
There is a possible denial of service vulnerability in Action View (Rails)  where specially crafted accept headers can cause action view to consume % cpu and make the server unresponsive.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Multiple cross-site scripting (XSS) vulnerabilities in the mail_to helper in Ruby on Rails before 2.3.11, and 3.x before 3.0.4, when javascript encoding is used, allow remote attackers to inject arbitrary web script or HTML via a crafted (1) name or (2) email value.