{"schemaVersion":3,"id":"UBUNTU-CVE-2021-41267","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Symfony/Http-Kernel is the HTTP kernel component for Symfony, a PHP framework for web and console applications and a set of reusable PHP components. Headers that are not part of the \"trusted_headers\" allowed list are ignored and protect users from \"Cache poisoning\" attacks. In Symfony 5.2, maintainers added support for the `X-Forwarded-Prefix` headers, but this header was accessible in SubRequest, even if it was not part of the \"trusted_headers\" allowed list. An attacker could leverage this opportunity to forge requests containing a `X-Forwarded-Prefix` header, leading to a web cache poisoning issue. Versions 5.3.12 and later have a patch to ensure that the `X-Forwarded-Prefix` header is not forwarded to subrequests when it is not trusted.","dates":{"published":"2021-11-24T19:15:00.000Z","modified":"2026-02-04T17:16:53.952Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":6.5,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","computed":true,"selection":"version-preference"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":6.5,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","exploitability":7.2,"impact":6,"computed":true}]},"epss":{"probability":null,"percentile":null,"severity":"unknown","asOf":null,"change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[],"last30":[]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[],"affected":[{"vendor":"ubuntu","product":"symfony","name":"symfony","label":"symfony","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/symfony","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://ubuntu.com/security/CVE-2021-41267","label":"ubuntu.com/security/CVE-2021-41267","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q","label":"github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q","hostname":"github.com","tags":["REPORT"]},{"url":"https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487","label":"github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487","hostname":"github.com","tags":["REPORT"]},{"url":"https://github.com/symfony/symfony/releases/tag/v5.3.12","label":"github.com/symfony/symfony/releases/tag/v5.3.12","hostname":"github.com","tags":["REPORT"]},{"url":"https://github.com/symfony/symfony/pull/44243","label":"github.com/symfony/symfony/pull/44243","hostname":"github.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-41267","label":"www.cve.org/CVERecord?id=CVE-2021-41267","hostname":"www.cve.org","tags":["REPORT"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":["CVE-2021-41267"]},"timeline":[{"kind":"published","date":"2021-11-24T19:15:00.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-02-04T17:16:53.952Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":26,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-21T16:26:39.816Z","stale":false,"partial":false}}