{"id":"CVE-2026-44309","state":"PUBLISHED","title":"gitsign verify accepts signatures over go-git-normalized bytes, enabling trust confusion on malformed commits","description":"Gitsign is a keyless Sigstore to signing tool for Git commits with your a GitHub / OIDC identity. Prior to 0.16.0, gitsign verify and gitsign verify-tag re-encode commit/tag objects through go-git's EncodeWithoutSignature before checking the signature, instead of verifying against the raw git object bytes. For malformed objects with duplicate tree headers, git-core and go-git parse different trees: git-core uses the first, go-git uses the second. A signature crafted over the go-git-normalized form (second tree) passes gitsign verify while git-core resolves the commit to a completely different tree. This breaks the invariant that a verified signature, the commit semantics git-core presents to users, and the object hash logged in Rekor all refer to the same content. This vulnerability is fixed in 0.16.0.","publishedAt":"2026-05-15T16:22:51.260Z","updatedAt":"2026-05-15T17:43:59.446Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["sigstore gitsign"],"affected":[{"vendor":"sigstore","product":"gitsign","versions":[{"version":"< 0.16.0","status":"affected"}]}],"references":["https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc"],"weaknesses":["CWE-347","CWE-295"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/44xxx/CVE-2026-44309.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-44309","state":"PUBLISHED","datePublished":"2026-05-15T16:22:51.260Z","dateUpdated":"2026-05-15T17:43:59.446Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-05T19:00:06.021Z"},"containers":{"cna":{"title":"gitsign verify accepts signatures over go-git-normalized bytes, enabling trust confusion on malformed commits","descriptions":[{"lang":"en","value":"Gitsign is a keyless Sigstore to signing tool for Git commits with your a GitHub / OIDC identity. Prior to 0.16.0, gitsign verify and gitsign verify-tag re-encode commit/tag objects through go-git's EncodeWithoutSignature before checking the signature, instead of verifying against the raw git object bytes. For malformed objects with duplicate tree headers, git-core and go-git parse different trees: git-core uses the first, go-git uses the second. A signature crafted over the go-git-normalized form (second tree) passes gitsign verify while git-core resolves the commit to a completely different tree. This breaks the invariant that a verified signature, the commit semantics git-core presents to users, and the object hash logged in Rekor all refer to the same content. This vulnerability is fixed in 0.16.0."}],"affected":[{"vendor":"sigstore","product":"gitsign","versions":[{"version":"< 0.16.0","status":"affected"}]}],"references":[{"url":"https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc","name":"https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","lang":"en","description":"CWE-347: Improper Verification of Cryptographic Signature","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295: Improper Certificate Validation","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-15T16:22:51.260Z"},"source":{"advisory":"GHSA-7rmh-48mx-2vwc","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-15T17:43:27.049597Z","id":"CVE-2026-44309","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-15T17:43:59.446Z"}}]}}}