Vulnerability Instance

Rack Header Parsing leads to Possible Denial of Service Vulnerability
# Possible Denial of Service Vulnerability in Rack Header Parsing

There is a possible denial of service vulnerability in the header parsing
routines in Rack.  This vulnerability has been assigned the CVE identifier
CVE-2024-26146.

Versions Affected:  All.
Not affected:       None
Fixed Versions:     2.0.9.4, 2.1.4.4, 2.2.8.1, 3.0.9.1

Impact
------
Carefully crafted headers can cause header parsing in Rack to take longer than
expected resulting in a possible denial of service issue. Accept and Forwarded
headers are impacted.

Ruby 3.2 has mitigations for this problem, so Rack applications using Ruby 3.2
or newer are unaffected.

Releases
--------
The fixed releases are available at the normal locations.

Workarounds
-----------
There are no feasible workarounds for this issue.

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.

* 2-0-header-redos.patch - Patch for 2.0 series
* 2-1-header-redos.patch - Patch for 2.1 series
* 2-2-header-redos.patch - Patch for 2.2 series
* 3-0-header-redos.patch - Patch for 3.0 series

Credits
-------

Thanks to [svalkanov](https://hackerone.com/svalkanov) for reporting this and
providing patches!