{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-109553", "assignerOrgId": "88ee5874-cf24-4952-aea0-31affedb7ff2", "state": "PUBLISHED", "assignerShortName": "Gitea", "dateReserved": "2026-10-14T20:08:45.856Z", "datePublished": "2026-10-18T18:51:31.037Z", "dateUpdated": "2026-10-19T20:19:06.039Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "88ee5874-cf24-4952-aea0-31affedb7ff2", "shortName": "Gitea", "dateUpdated": "2026-10-18T18:51:31.037Z"}, "title": "Gitea SSH certificate principal impersonation of other users", "descriptions": [{"lang": "en", "value": "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."}], "affected": [{"vendor": "Gitea", "product": "Gitea", "packageName": "gitea.dev", "defaultStatus": "unaffected", "versions": [{"version": "0", "status": "affected", "lessThanOrEqual": "28.1.0", "versionType": "semver"}]}], "references": [{"url": "https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3", "name": "GitHub Security Advisory GHSA-vcp6-2qc6-gvq3", "tags": ["vendor-advisory"]}, {"url": "https://github.com/go-gitea/gitea/pull/39839", "name": "Fix: go-gitea/gitea pull request #39839", "tags": ["patch"]}, {"url": "https://github.com/go-gitea/gitea/pull/39847", "name": "Fix backport to release/v28: go-gitea/gitea pull request #39847", "tags": ["patch"]}, {"url": "https://blog.gitea.com/release-of-28.2.0/", "name": "Gitea 28.2.0 release announcement", "tags": ["release-notes"]}, {"url": "https://github.com/go-gitea/gitea/releases/tag/v28.2.0", "name": "go-gitea/gitea v28.2.0 release", "tags": ["release-notes"]}], "credits": [{"lang": "en", "value": "https://github.com/DshtAnger", "type": "reporter"}, {"lang": "en", "value": "https://github.com/silverwind", "type": "remediation developer"}, {"lang": "en", "value": "https://github.com/wxiaoguang", "type": "remediation developer"}, {"lang": "en", "value": "https://github.com/bircni", "type": "remediation developer"}]}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-10-19T20:19:01.147709Z", "id": "CVE-2026-109553", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T20:19:06.039Z"}}]}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "packageName": "gitea.dev", "product": "Gitea", "vendor": "Gitea", "versions": [{"lessThanOrEqual": "28.1.0", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "88ee5874-cf24-4952-aea0-31affedb7ff2"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-109553", "lastModified": "2026-10-19T21:17:04.780", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-109553", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-19T20:19:01.147709Z", "version": "2.0.3"}}]}, "published": "2026-10-18T19:16:32.997", "references": [{"source": "88ee5874-cf24-4952-aea0-31affedb7ff2", "url": "https://blog.gitea.com/release-of-28.2.0/"}, {"source": "88ee5874-cf24-4952-aea0-31affedb7ff2", "url": "https://github.com/go-gitea/gitea/pull/39839"}, {"source": "88ee5874-cf24-4952-aea0-31affedb7ff2", "url": "https://github.com/go-gitea/gitea/pull/39847"}, {"source": "88ee5874-cf24-4952-aea0-31affedb7ff2", "url": "https://github.com/go-gitea/gitea/releases/tag/v28.2.0"}, {"source": "88ee5874-cf24-4952-aea0-31affedb7ff2", "url": "https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3"}], "sourceIdentifier": "88ee5874-cf24-4952-aea0-31affedb7ff2", "vulnStatus": "Awaiting Analysis"}

{}