{"id":"CVE-2023-27539","aliases":["GHSA-c6qg-cjj8-47qp"],"url":"https://o3.security/vulnerability/CVE-2023-27539","summary":"Possible Denial of Service Vulnerability in Rack's header parsing","details":"There is a denial of service vulnerability in the header parsing component of Rack. This vulnerability has been assigned the CVE identifier CVE-2023-27539.\n\nVersions Affected: >= 2.0.0 Not affected: None. Fixed Versions: 2.2.6.4, 3.0.6.1\n\n# Impact\nCarefully crafted input can cause header parsing in Rack to take an unexpected amount of time, possibly resulting in a denial of service attack vector. Any applications that parse headers using Rack (virtually all Rails applications) are impacted.\n\n# Workarounds\nSetting Regexp.timeout in Ruby 3.2 is a possible workaround.\n","published":"2025-01-09T00:33:47.737Z","modified":"2026-08-12T03:51:32.524659328Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"RubyGems","name":"rack","fixedVersion":"2.2.6.4"},{"ecosystem":"RubyGems","name":"rack","fixedVersion":"3.0.6.1"}],"fix":{"url":"https://github.com/rack/rack/commit/231ef369ad0b542575fb36c74fcfcfabcf6c530c","label":"rack/rack@231ef36"},"references":[{"type":"WEB","url":"https://discuss.rubyonrails.org/t/cve-2023-27539-possible-denial-of-service-vulnerability-in-racks-header-parsing/82466"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2023/04/msg00017.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/27xxx/CVE-2023-27539.json"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-c6qg-cjj8-47qp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-27539"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20231208-0016/"},{"type":"ADVISORY","url":"https://www.debian.org/security/2023/dsa-5530"},{"type":"FIX","url":"https://github.com/rack/rack/commit/231ef369ad0b542575fb36c74fcfcfabcf6c530c"},{"type":"FIX","url":"https://github.com/rack/rack/commit/ee7919ea04303717858be1c3f16b406adc6d8cff"},{"type":"PACKAGE","url":"https://github.com/rack/rack"},{"type":"WEB","url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2023-27539.yml"},{"type":"WEB","url":"https://security.netapp.com/advisory/ntap-20231208-0016"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:32.524659328Z"}}