There is a possible DoS vulnerability in the Token Authentication logic in
Action Controller. This vulnerability has been assigned the CVE identifier
CVE-2021-22904.
Versions Affected: >= 4.0.0
Not affected: < 4.0.0
Fixed Versions: 6.1.3.2, 6.0.3.7, 5.2.4.6, 5.2.6
Impact
------
Impacted code uses `authenticate_or_request_with_http_token` or
`authenticate_with_http_token` for request authentication. Impacted code will
look something like this:
```
class PostsController < ApplicationController
before_action :authenticate
private
def authenticate
authenticate_or_request_with_http_token do |token, options|
# ...
end
end
end
```
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
-----------
The following monkey patch placed in an initializer can be used to work around
the issue:
```ruby
module ActionController::HttpAuthentication::Token
AUTHN_PAIR_DELIMITERS = /(?:,|;|\t)/
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-http-authentication-dos.patch - Patch for 5.2 series
* 6-0-http-authentication-dos.patch - Patch for 6.0 series
* 6-1-http-authentication-dos.patch - Patch for 6.1 series
Please note that only the 6.1.Z, 6.0.Z, and 5.2.Z 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
-------
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