CVE-2026-64655 GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching
Attackers can bypass GitHub CLI attestation verification by using regex metacharacters in signer names, undermining supply chain security for CI/CD pipelines.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-64655?
CVE-2026-64655 is a low-severity vulnerability in cli, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-185
Which versions are affected by CVE-2026-64655?
4 open source packages ship an affected version, including github.com/cli/cli/v2 and github.com/cli/cli.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cli/cli/v2 Go | All versions | 2.97.0 |
github.com/cli/cli/v2 Go | All versions | 2.97.0 |
github.com/cli/cli/v2 Go | All versions | 2.97.0 |
github.com/cli/cli Go | All versions | None |
How do I fix CVE-2026-64655?
Upgrade github.com/cli/cli/v2 to 2.97.0 or later.
Is CVE-2026-64655 being exploited?
There is no known exploitation of CVE-2026-64655 in the wild and no public exploit code.
Sources
Also known as AZL-95472, DEBIAN-CVE-2026-64655, GHSA-mm27-mwq9-fr5g, GO-2026-6767, MINI-2q9m-9fv3-75r5, MINI-6vrj-m5jq-28jp and 1 more.