Description
A regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-Match header. A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophic backtracking, when on a version of Ruby below 3.2.0. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should either upgrade or use one of the workarounds immediately.
Affected products
rubyonrails: rails; ruby-lang: ruby; debian: debian linux
References6
- discuss.rubyonrails.org/t/cve-2023-22795-possible-redos-based-d… PatchVendor Advisory
- discuss.rubyonrails.org/t/cve-2023-22795-possible-redos-based-d… PatchVendor Advisory
- security.netapp.com/advisory/ntap-20240202-0010/
- www.debian.org/security/2023/dsa-5372 Third Party Advisory
- security.netapp.com/advisory/ntap-20240202-0010/
- www.debian.org/security/2023/dsa-5372 Third Party Advisory
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 2% percentile: 83 · as of 6 November 2026
- CWE
- CWE-400CWE-1333
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.