{"id":"CVE-2026-64655","state":"PUBLISHED","title":"GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching","description":"GitHub CLI (gh) is GitHub’s official command line tool. Prior to 2.97.0, gh attestation verify  builds the certificate Subject Alternative Name matcher from the --signer-repo and --signer-workflow  flag values without escaping regex metacharacters, so a user-supplied repository or workflow name is treated as a regular expression rather than a literal string. Because GitHub permits characters such as  `.`  in organization, repository, and workflow path names and  `.`  is a regex wildcard, an attacker can register a lookalike name (for example github/artifact.attestations-workflows) that satisfies a matcher intended for a different trusted signer (github/artifact-attestations-workflows), bypassing the intended Sigstore attestation verification. Exploitation requires the attacker to create a plausible lookalike repository and produce valid attestations from it, which could undermine supply chain verification for CI/CD pipelines or policy gates that pin trust to a specific signing workflow. This issue is fixed in version 2.97.0.","publishedAt":"2026-08-06T18:41:54.628Z","updatedAt":"2026-08-08T02:23:17.134Z","severity":{"score":2.1,"label":"Low","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["cli cli"],"affected":[{"vendor":"cli","product":"cli","versions":[{"version":"< 2.97.0","status":"affected"}]}],"references":["https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g","https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55","https://github.com/cli/cli/releases/tag/v2.97.0"],"weaknesses":["CWE-185"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64655.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64655","state":"PUBLISHED","datePublished":"2026-08-06T18:41:54.628Z","dateUpdated":"2026-08-08T02:23:17.134Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-20T17:11:30.896Z"},"containers":{"cna":{"title":"GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching","descriptions":[{"lang":"en","value":"GitHub CLI (gh) is GitHub’s official command line tool. Prior to 2.97.0, gh attestation verify  builds the certificate Subject Alternative Name matcher from the --signer-repo and --signer-workflow  flag values without escaping regex metacharacters, so a user-supplied repository or workflow name is treated as a regular expression rather than a literal string. Because GitHub permits characters such as  `.`  in organization, repository, and workflow path names and  `.`  is a regex wildcard, an attacker can register a lookalike name (for example github/artifact.attestations-workflows) that satisfies a matcher intended for a different trusted signer (github/artifact-attestations-workflows), bypassing the intended Sigstore attestation verification. Exploitation requires the attacker to create a plausible lookalike repository and produce valid attestations from it, which could undermine supply chain verification for CI/CD pipelines or policy gates that pin trust to a specific signing workflow. This issue is fixed in version 2.97.0."}],"affected":[{"vendor":"cli","product":"cli","versions":[{"version":"< 2.97.0","status":"affected"}]}],"references":[{"url":"https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g","name":"https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55","name":"https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55","tags":["x_refsource_MISC"]},{"url":"https://github.com/cli/cli/releases/tag/v2.97.0","name":"https://github.com/cli/cli/releases/tag/v2.97.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"ACTIVE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","baseScore":2.1,"baseSeverity":"LOW","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-185","lang":"en","description":"CWE-185: Incorrect Regular Expression","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-06T18:41:54.628Z"},"source":{"advisory":"GHSA-mm27-mwq9-fr5g","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-08T02:23:02.313002Z","id":"CVE-2026-64655","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-08T02:23:17.134Z"}}]}}}