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.
Scoring
- Severity
- LOW
- CVSS base score
- 2.1
- CVSS 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
- EPSS probability
- 0.33%
- CWE
- CWE-185
- Published
- 2026-08-06
- Last modified
- 2026-08-08
Affected products
- cli cli
Weakness type
Related vulnerabilities
- CVE-2026-73425 — @astrojs/netlify generates an overly-broad Netlify Image CDN allowlist because remotePatterns.pathname metacharacters are not escaped
- CVE-2026-45065 — Symfony: UrlGenerator Route-Requirement Bypass via Unanchored Regex Alternation → Off-Site //host URL Injection
- CVE-2026-56021 — Webmin information disclosure via regex pattern
- CVE-2026-47674 — Hono: IP Restriction bypasses static deny rules for non-canonical IPv6
- CVE-2026-48147 — Budibase: Unanchored Regex in `matchers.ts` Allows CSRF Bypass via Query String Injection in Budibase Worker
- CVE-2026-4296 — Incorrect Regular Expression vulnerability in GitHub Enterprise Server allowed unauthorized access to user accounts via OAuth callback URL validation bypass
- CVE-2026-25542 — Tekton Pipelines: VerificationPolicy regex pattern bypass via substring matching
- CVE-2026-39350 — Istio AuthorizationPolicy Incorrect Regex Matching of Dots in serviceAccounts Fields Allows Policy Bypass