CVE-2025-27220
In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.
02 / AFFECTED SOFTWARE
Affected packages
14 explicit affected versions
18 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
There is a possibility for Regular expression Denial of Service (ReDoS) by in the cgi gem. This vulnerability has been assigned the CVE identifier CVE-2025-27220. We recommend upgrading the cgi gem. ## Details The regular expression used in `CGI::Util#escapeElement` is vulnerable to ReDoS. The crafted input could lead to a high CPU consumption. This vulnerability only affects Ruby 3.1 and 3.2. If you are using these versions, please update CGI gem to version 0.3.5.1, 0.3.7, 0.4.2 or later. ## Affected versions cgi gem versions <= 0.3.5, 0.3.6, 0.4.0 and 0.4.1. ## Credits Thanks to svalkanov for discovering this issue. Also thanks to nobu for fixing this vulnerability.
In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.
05 / REFERENCES
Further evidence
- https://github.com/ruby/cgi
- https://github.com/ruby/cgi/pull/52
- https://github.com/ruby/cgi/pull/53
- https://github.com/ruby/cgi/pull/54
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2025-27220.yml
- https://hackerone.com/reports/2890322
- https://lists.debian.org/debian-lts-announce/2025/03/msg00008.html
- https://nvd.nist.gov/vuln/detail/CVE-2025-27220
- https://www.cve.org/CVERecord?id=CVE-2025-27220
- https://www.ruby-lang.org/en/news/2025/02/26/security-advisories
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/27xxx/CVE-2025-27220.json