CVE-2025-27219

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-03-04 · updated 2026-06-17
Weakness: CWE-770

Description

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.

Affected products

ruby-lang CGI: before 0.3.5.1; from 0.4.0 before 0.4.2; 0.3.6 — fixed in 0.3.5.1, 0.4.2

How to fix

Upgrade to a fixed version: ruby-lang CGI 0.3.5.1, 0.4.2. Check the vendor advisory for mitigations.

References

https://github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2025-27219.yml
https://hackerone.com/reports/2936778
https://lists.debian.org/debian-lts-announce/2025/03/msg00008.html

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