CVE-2026-64655
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.
- Score
- CVSS 4.0 2.1 Low
- Status
- Awaiting Analysis - security-advisories@github.com
- Published
- 2026-08-06
- Last modified
- 2026-08-08
- Weaknesses
- CWE-185
Affected products
References
- https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55
- https://github.com/cli/cli/releases/tag/v2.97.0
- https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g
