[CVE-2023-27539] Possible Denial of Service Vulnerability in Rack's header parsing

Possible Denial of Service Vulnerability in Rack’s header parsing

There is a denial of service vulnerability in the header parsing component of Rack. This vulnerability has been assigned the CVE identifier CVE-2023-27539.

Versions Affected: >= 2.0.0 Not affected: None. Fixed Versions:,


Carefully crafted input can cause header parsing in Rack to take an unexpected amount of time, possibly resulting in a denial of service attack vector. Any applications that parse headers using Rack (virtually all Rails applications) are impacted.


The fixed releases are available at the normal locations.


Setting Regexp.timeout in Ruby 3.2 is a possible workaround.


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.

  • 2-2-header-redos.patch - Patch for 2.2 series
  • 3-0-header-redos.patch - Patch for 3.0 series


Thank you ooooooo_q for reporting this!

2-2-header-redos.patch (974 Bytes) 3-0-header-redos.patch (974 Bytes)

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