CVE-2026-64655GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching
- 2.1LowCVSS base score
- 0.34%Exploitation in 30 daysEPSS · top 72% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 17 days later
· 17 days later
Published
- 2 days later
· 2 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | Low2.1 | 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 |
| NVDNVD · Awaiting Analysis | 4.0 | Low2.1 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.34% · top 72% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 2.1.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/cli/cli/v2GHSA-mm27-mwq9-fr5g (opens in a new tab)
References
References3
- https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g (opens in a new tab)x_refsource_CONFIRM
- https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55 (opens in a new tab)x_refsource_MISC
- https://github.com/cli/cli/releases/tag/v2.97.0 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-54222 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-mm27-mwq9-fr5g (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-64655)Record last updated .