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Vulnerability record · CVE-2021-41819 · published 1 January 2022

CVE-2021-41819: Ruby-lang cgi reliance on cookies without validation vulnerability

Ruby Lang · Cgi

CGI::Cookie.parse in Ruby through 2.6.8 mishandles security prefixes in cookie names. This also affects the CGI gem through 0.3.0 for Ruby.

7.5 CVSS 3.1 High EPSS 2.9% · top 13.4% CWE-565 · Reliance on cookies without validation
7.5CVSS 3.1 base score, v2 5.0
2.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
9Affected product versions listed by NVD
12References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

CGI::Cookie.parse in Ruby through 2.6.8 mishandles security prefixes in cookie names. This also affects the CGI gem through 0.3.0 for Ruby.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

9 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://hackerone.com/reports/910552 Permissions RequiredThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUXQCH6FRKANCVZO2Q7D2SQ
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UTOJGS5IEFDK3UOO7IY4OTT
https://security.gentoo.org/glsa/202401-27
https://security.netapp.com/advisory/ntap-20220121-0003/ Third Party Advisory
https://www.ruby-lang.org/en/news/2021/11/24/cookie-prefix-spoofing-in-cgi-cookie-parse-cve-2021-41819/ ExploitVendor Advisory
https://hackerone.com/reports/910552 Permissions RequiredThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUXQCH6FRKANCVZO2Q7D2SQ
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UTOJGS5IEFDK3UOO7IY4OTT
https://security.gentoo.org/glsa/202401-27
https://security.netapp.com/advisory/ntap-20220121-0003/ Third Party Advisory
https://www.ruby-lang.org/en/news/2021/11/24/cookie-prefix-spoofing-in-cgi-cookie-parse-cve-2021-41819/ ExploitVendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-41819), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.