What’s Vulnerable › Vulnerabilities
CVE-2021-41819
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 3.2% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2022-01-01 · updated 2026-06-17
- Weakness: CWE-565
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.
Affected products
- Debian Linux: 9.0, 10.0, 11.0
- Fedoraproject Fedora: 34, 35
- openSUSE Factory: all versions
- openSUSE Leap: 15.2
- Red Hat Enterprise Linux: 8.0
- RedHat Software Collections: all versions
- ruby-lang CGI: 0.1.0, 0.2.0, 0.3.0
- Ruby: through 2.6.8; from 2.7.0 before 2.7.5; from 3.0.0 before 3.0.3 — fixed in 2.7.5, 3.0.3
- SUSE Linux Enterprise: 11.0-sp1, 12.0, 15.0
How to fix
Upgrade to a fixed version: Ruby 2.7.5, 3.0.3. Check the vendor advisory for mitigations.
References
- https://hackerone.com/reports/910552
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUXQCH6FRKANCVZO2Q7D2SQX33FP3KWN/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UTOJGS5IEFDK3UOO7IY4OTTFGHGLSWZF/
- https://security.gentoo.org/glsa/202401-27
- https://security.netapp.com/advisory/ntap-20220121-0003/
- https://www.ruby-lang.org/en/news/2021/11/24/cookie-prefix-spoofing-in-cgi-cookie-parse-cve-2021-41819/
- https://hackerone.com/reports/910552
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUXQCH6FRKANCVZO2Q7D2SQX33FP3KWN/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UTOJGS5IEFDK3UOO7IY4OTTFGHGLSWZF/
- https://security.gentoo.org/glsa/202401-27
- https://security.netapp.com/advisory/ntap-20220121-0003/
- https://www.ruby-lang.org/en/news/2021/11/24/cookie-prefix-spoofing-in-cgi-cookie-parse-cve-2021-41819/
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