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Vulnerabilities

Vulnerability · CVE-2026-64655

GitHub CLI allows attestation verification bypass through unescaped regex metacharacters

Published Oct 15, 2026 · catalog updated Oct 15, 2026 · GitHub CLI allows attestation

Check if you run it

No confirmed exploitation is on record for CVE-2026-64655. EPSS is 0.34%. Act only if a listed version of GitHub CLI allows attestation is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (GitHub CLI allows attestation).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.34%
Remediation
Version ranges on file
Affected products
Go github.com/cli/cli/v2 · go github.com/cli/cli/v2 · golang github.com

### Summary A security vulnerability has been identified in GitHub CLI that could allow attestation verification bypass when using with or flags. GitHub CLI builds the certificate matcher from these flag values without escaping regex metacharacters, so a repository or workflow name is treated as a regular expression rather than a literal string. GitHub permits characters such as in organization, repository, and workflow path names, and is a regex wildcard, so a malicious actor can create a lookalike name that satisfies a matcher intended for a different, trusted signer. ### Details GitHub CLI constructs a regular expression from the and values and matches it against the signing certificate's SAN (Subject Alternative Name) during Sigstore attestation verification. The user-supplied value is interpolated into the pattern without escaping regex metacharacters, so any metacharacter permitted in a GitHub path is interpreted as regex syntax instead of a literal character. The most practical case is , which GitHub allows in org/repo names and is a regex wildcard meaning "any single character." For example, an attacker-controlled repository named: matches a verifier configured for the trusted signer: because the unescaped in the constructed pattern matches the in the attacker's name (and any other single character at that position). This affected the and flags but did not affect the and flags which include an exact string comparison. In , the GitHub CLI escapes the user-supplied signer values before they are incorporated into the SAN matcher, so they are matched as literal strings. ### Impact The practical impact is limited, exploitation requires the attacker to create a plausible lookalike repository name and produce valid Sigstore attestations from it. This could undermine supply chain verification for CI/CD pipelines or policy gates that use these flags to pin trust to a specific signing workflow. ### Remediation and Mitigation 1. Upgrade to or later, which escapes signe

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Go github.com/cli/cli/v20 → 2.97.0
  • go github.com/cli/cli/v2< 2.97.0
  • golang github.comversion unspecified

How to fix CVE-2026-64655

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-64655. EPSS is 0.34%. Act only if a listed version of GitHub CLI allows attestation is installed.

Which versions are affected?

Compare what you have installed with 0 → 2.97.0, < 2.97.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-185. EPSS 0.34%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 15, 2026 · GitHub Advisory Database

    Detected

    ### Summary A security vulnerability has been identified in GitHub CLI that could allow attestation verification bypass when using with or flags. GitHub CLI builds the certificate matcher from these flag values without escaping regex metacharacters, so a repository or workflow name is treated as a regular expression rather than a literal string. GitHub permits characters such as in organization, r

  2. Oct 15, 2026 · GitHub Advisory Database

    Fix available

    github.com/cli/cli/v2 fixed in 2.97.0

  3. Oct 15, 2026 · GitHub Advisory Database

    Fix available

    github.com/cli/cli/v2 fixed in 2.97.0

  4. Oct 15, 2026 · GitHub Advisory Database

    Updated

    ### Summary A security vulnerability has been identified in GitHub CLI that could allow attestation verification bypass when using with or flags. GitHub CLI builds the certificate matcher from these flag values without escaping regex metacharacters, so a repository or workflow name is treated as a regular expression rather than a literal string. GitHub permits characters such as in organization, r

Sources

  • CVE.orgVulnerability recordCVE-2026-64655

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-64655

    30-day exploitation probability 0.3%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-mm27-mwq9-fr5g

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-64655

    A security vulnerability has been identified in GitHub CLI that could allow attestation verification bypass when using gh attestation verify with &ndash;signer-repo or &ndash;signer-workflow flags. GitHub CLI builds the certificate matcher from these flag values without escaping regex metacharacters, so a repository or workflow name is treated as a regular expression rather than a literal string.

    advisories.gitlab.com
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-mm27-mwq9-fr5g

    GitHub CLI allows attestation verification bypass through unescaped regex metacharacters

    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.