GitHub CLI allows attestation verification bypass through unescaped regex metacharacters

{
  "id": "e297503c4217edfeb24ba881d317cd6d020a62f79f6e2d1fe89601fde00ec6ee",
  "url": "https://osv.dev/vulnerability/GHSA-mm27-mwq9-fr5g",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "GitHub CLI allows attestation verification bypass through unescaped regex metacharacters",
    "summary": "### Summary A security vulnerability has been identified in GitHub CLI that could allow attestation verification bypass when using `gh attestation verify` with `--signer-repo` or `--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. 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 `--signer-repo` and `--signer-workflow` 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: `github/artifact.attestations-workflows` matches a verifier configured for the trusted signer: `github/artifact-attestations-workflows` because the unescaped `.` in the constructed pattern matches the `-` in the attacker's name (and a",
    "evidence": "osv:GHSA-mm27-mwq9-fr5g",
    "products": [
      {
        "name": {
          "value": "github.com/cli/cli/v2",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.97.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "GHSA-mm27-mwq9-fr5g",
      "aliases": [
        "CVE-2026-64655",
        "GHSA-mm27-mwq9-fr5g",
        "GO-2026-6767"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.97.0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/cli/cli/v2",
            "purl": "pkg:golang/github.com/cli/cli/v2",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-mm27-mwq9-fr5g/GHSA-mm27-mwq9-fr5g.json"
          }
        }
      ],
      "modified": "2026-10-19T21:41:04.715150068Z",
      "provider": "osv",
      "references": [
        "https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64655",
        "https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55",
        "https://github.com/cli/cli",
        "https://github.com/cli/cli/releases/tag/v2.97.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-185"
        ],
        "severity": "LOW",
        "github_reviewed": true,
        "nvd_published_at": "2026-08-06T22:18:13Z",
        "github_reviewed_at": "2026-10-15T18:08:20Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64655",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 376771,
  "published_at": "2026-10-15T18:08:20+00:00"
}

{
  "id": "ba92fef0111e26aafea0fa9a9ca0c784b16e3c27a5904f3aeb13a21dc3ca1038",
  "url": "https://osv.dev/vulnerability/GO-2026-6767",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "GitHub CLI allows attestation verification bypass through unescaped regex metacharacters in github.com/cli/cli",
    "summary": "GitHub CLI allows attestation verification bypass through unescaped regex metacharacters in github.com/cli/cli",
    "evidence": "osv:GO-2026-6767",
    "products": [
      {
        "name": {
          "value": "github.com/cli/cli",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "github.com/cli/cli/v2",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.97.0",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "GO-2026-6767",
      "aliases": [
        "CVE-2026-64655",
        "GHSA-mm27-mwq9-fr5g",
        "GO-2026-6767"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/cli/cli",
            "purl": "pkg:golang/github.com/cli/cli",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6767.json"
          },
          "ecosystem_specific": {}
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.97.0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/cli/cli/v2",
            "purl": "pkg:golang/github.com/cli/cli/v2",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6767.json"
          },
          "ecosystem_specific": {}
        }
      ],
      "modified": "2026-10-19T21:31:49.979387869Z",
      "provider": "osv",
      "references": [
        "https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64655",
        "https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55",
        "https://github.com/cli/cli/releases/tag/v2.97.0"
      ],
      "provider_metadata": {
        "url": "https://pkg.go.dev/vuln/GO-2026-6767",
        "review_status": "UNREVIEWED"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64655",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 376696,
  "published_at": "2026-10-19T21:08:35+00:00"
}