{"id":"UBUNTU-CVE-2026-64655","details":"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.","modified":"2026-08-13T00:13:01Z","published":"2026-08-06T22:18:00Z","upstream":["CVE-2026-64655"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-64655"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-64655"},{"type":"REPORT","url":"https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55"},{"type":"REPORT","url":"https://github.com/cli/cli/releases/tag/v2.97.0"},{"type":"REPORT","url":"https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g"}],"affected":[{"package":{"name":"gh","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/gh?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.4.0+dfsg1-1","2.4.0+dfsg1-2"],"ecosystem_specific":{"binaries":[{"binary_name":"gh","binary_version":"2.4.0+dfsg1-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64655.json"}},{"package":{"name":"gh","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/gh?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.27.0+dfsg1-1build1","2.30.0-2","2.35.0-1","2.40.1+dfsg1-1","2.42.1-1","2.43.1-1","2.44.1-1","2.44.1-2","2.45.0-1","2.45.0-1build1","2.45.0-1ubuntu0.1","2.45.0-1ubuntu0.2","2.45.0-1ubuntu0.2+esm1","2.45.0-1ubuntu0.2+esm2","2.45.0-1ubuntu0.3","2.45.0-1ubuntu0.3+esm1","2.45.0-1ubuntu0.3+esm2","2.45.0-1ubuntu0.3+esm3"],"ecosystem_specific":{"binaries":[{"binary_version":"2.45.0-1ubuntu0.3+esm3","binary_name":"gh"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64655.json"}},{"package":{"name":"gh","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/gh?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.46.0-3","2.46.0-4","2.46.0-4ubuntu0.26.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"gh","binary_version":"2.46.0-4ubuntu0.26.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64655.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"},{"type":"Ubuntu","score":"medium"}]}