{"schemaVersion":3,"id":"CVE-2026-109553","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Gitea resolved the principals of an SSH certificate by searching the content of all stored public keys instead of only principal keys. When Gitea trusts a user certificate authority (`SSH_TRUSTED_USER_CA_KEYS`) and accepts arbitrary principals (`SSH_AUTHORIZED_PRINCIPALS_ALLOW=anything`), a user could register another user's public key line as their own principal, or a holder of a certificate signed by that authority could list it, and then authenticate as the owner of that key through the HTTP signature API and the built-in SSH server. Instances that do not trust a user certificate authority are not affected.","dates":{"published":"2026-10-18T18:51:31.037Z","modified":"2026-10-19T20:19:06.039Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.5,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00198,"percentile":0.08925,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-19T00:00:00.000Z","score":0.00104,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00198,"percentile":0.08925}],"last30":[{"date":"2026-10-19T00:00:00.000Z","score":0.00104,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00198,"percentile":0.08925}]},"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":"gitea","product":"gitea","name":"Gitea","label":"gitea","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≤ 28.1.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"≤ 28.1.0","eol":null,"hubHref":"/vendor/gitea/gitea"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3","label":"github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3","hostname":"github.com","tags":["Vendor Advisory"]},{"url":"https://github.com/go-gitea/gitea/pull/39839","label":"github.com/go-gitea/gitea/pull/39839","hostname":"github.com","tags":["Patch"]},{"url":"https://github.com/go-gitea/gitea/pull/39847","label":"github.com/go-gitea/gitea/pull/39847","hostname":"github.com","tags":["Patch"]},{"url":"https://blog.gitea.com/release-of-28.2.0/","label":"blog.gitea.com/release-of-28.2.0/","hostname":"blog.gitea.com","tags":["Release Notes"]},{"url":"https://github.com/go-gitea/gitea/releases/tag/v28.2.0","label":"github.com/go-gitea/gitea/releases/tag/v28.2.0","hostname":"github.com","tags":["Release Notes"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-18T18:51:31.037Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-19T20:19:06.039Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":30,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T18:25:36.468Z","stale":false,"partial":false}}