{"schema":"threatline.record/2","record":{"id":"CVE-2026-109553","aliases":["GHSA-vcp6-2qc6-gvq3"],"summary":"Gitea SSH certificate principal impersonation of other users","details":"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.","categories":["Unclassified"],"product":"Gitea","vendor":"Gitea","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-109553","source_modified_at":"2026-10-19T20:19:06.039Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Gitea","vendor":"Gitea","versions":[{"lessThanOrEqual":"28.1.0","status":"affected","version":"0","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"GitHub Advisory Database","source_url":"https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3","source_modified_at":"2026-10-20T03:04:56Z","fetched_at":"2026-10-23T18:58:35.272684Z","package":{"ecosystem":"go","name":"gitea.dev"},"range":"<= 28.1.0"}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3","source_modified_at":"2026-10-20T03:04:56Z","fetched_at":"2026-10-23T18:58:35.272684Z","package":{"ecosystem":"go","name":"gitea.dev"},"version":"28.2.0"}],"cvss":7.5,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00198,"percentile":0.08989,"score_date":"2026-10-23"},"published_at":"2026-10-18T18:51:31.037Z","modified_at":"2026-10-20T03:04:56Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-109553","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T20:19:06.039Z"},{"source":"GitHub Advisory Database","url":"https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3","fetched_at":"2026-10-23T18:58:35.272684Z","source_modified_at":"2026-10-20T03:04:56Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-109553","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","GitHub Advisory Database","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3","tags":["vendor-advisory"]},{"source":"CVE List","url":"https://github.com/go-gitea/gitea/pull/39839","tags":["patch"]},{"source":"CVE List","url":"https://github.com/go-gitea/gitea/pull/39847","tags":["patch"]},{"source":"CVE List","url":"https://blog.gitea.com/release-of-28.2.0/","tags":["release-notes"]},{"source":"CVE List","url":"https://github.com/go-gitea/gitea/releases/tag/v28.2.0","tags":["release-notes"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CISA ADP","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"total","assessed_at":"2026-10-19T20:19:01.147709Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-20T03:04:56Z","content_hash":"af97082b36cd2f260ba79e61d46cd621cb78e2bf725973e34b49909e5b5a7851"}}