Vulnerability-Lookup

UBUNTU-CVE-2026-64655 (CVE-2026-64655)

Vulnerability from osv_ubuntu – Published: 2026-08-06 22:18 – Updated: 2026-08-13 00:13 – Source website

Details

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.

Severity

2.1 (Low)


                    
                      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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-64655	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-64655	REPORT
	https://github.com/cli/cli/commit/55dbb4dc6b7edb1…	REPORT
	https://github.com/cli/cli/releases/tag/v2.97.0	REPORT
	https://github.com/cli/cli/security/advisories/GH…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gh",
            "binary_version": "2.4.0+dfsg1-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "gh",
        "purl": "pkg:deb/ubuntu/gh@2.4.0+dfsg1-2?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.4.0+dfsg1-1",
        "2.4.0+dfsg1-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gh",
            "binary_version": "2.45.0-1ubuntu0.3+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "gh",
        "purl": "pkg:deb/ubuntu/gh@2.45.0-1ubuntu0.3+esm3?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.27.0+dfsg1-1build1",
        "2.30.0-2",
        "2.35.0-1",
        "2.40.1+dfsg1-1",
        "2.42.1-1",
        "2.43.1-1",
        "2.44.1-1",
        "2.44.1-2",
        "2.45.0-1",
        "2.45.0-1build1",
        "2.45.0-1ubuntu0.1",
        "2.45.0-1ubuntu0.2",
        "2.45.0-1ubuntu0.2+esm1",
        "2.45.0-1ubuntu0.2+esm2",
        "2.45.0-1ubuntu0.3",
        "2.45.0-1ubuntu0.3+esm1",
        "2.45.0-1ubuntu0.3+esm2",
        "2.45.0-1ubuntu0.3+esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gh",
            "binary_version": "2.46.0-4ubuntu0.26.04.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:26.04:LTS",
        "name": "gh",
        "purl": "pkg:deb/ubuntu/gh@2.46.0-4ubuntu0.26.04.1~esm1?arch=source\u0026distro=esm-apps/resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.46.0-3",
        "2.46.0-4",
        "2.46.0-4ubuntu0.26.04.1~esm1"
      ]
    }
  ],
  "aliases": [],
  "details": "GitHub CLI (gh) is GitHub\u2019s official command line tool. Prior to 2.97.0, gh attestation verify\u00a0 builds the certificate Subject Alternative Name matcher from the --signer-repo and --signer-workflow\u00a0 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 \u00a0`.`\u00a0 in organization, repository, and workflow path names and \u00a0`.`\u00a0 is a regex wildcard, an attacker can register a lookalike name (for example\u00a0github/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.",
  "id": "UBUNTU-CVE-2026-64655",
  "modified": "2026-08-13T00:13:01Z",
  "published": "2026-08-06T22:18:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-64655"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-64655"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/cli/cli/releases/tag/v2.97.0"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-64655"
  ]
}

CVE-2026-64655 (GCVE-0-2026-64655)

Vulnerability from cvelistv5 – Published: 2026-08-06 18:41 – Updated: 2026-08-08 02:23

Title

GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching

Summary

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.

Severity

2.1 (Low)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-08 02:23 UTC

CWE

CWE-185 - Incorrect Regular Expression

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7637 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/cli/cli/security/advisories/GH…	x_refsource_CONFIRM
https://github.com/cli/cli/commit/55dbb4dc6b7edb1…	x_refsource_MISC
https://github.com/cli/cli/releases/tag/v2.97.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
cli	cli	Affected: < 2.97.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-64655",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-08T02:23:02.313002Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-08T02:23:17.134Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "cli",
          "vendor": "cli",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.97.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "GitHub CLI (gh) is GitHub\u2019s official command line tool. Prior to 2.97.0, gh attestation verify\u00a0 builds the certificate Subject Alternative Name matcher from the --signer-repo and --signer-workflow\u00a0 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 \u00a0`.`\u00a0 in organization, repository, and workflow path names and \u00a0`.`\u00a0 is a regex wildcard, an attacker can register a lookalike name (for example\u00a0github/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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.1,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "LOW",
            "userInteraction": "ACTIVE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-185",
              "description": "CWE-185: Incorrect Regular Expression",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-06T18:41:54.628Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/cli/cli/security/advisories/GHSA-mm27-mwq9-fr5g"
        },
        {
          "name": "https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55"
        },
        {
          "name": "https://github.com/cli/cli/releases/tag/v2.97.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cli/cli/releases/tag/v2.97.0"
        }
      ],
      "source": {
        "advisory": "GHSA-mm27-mwq9-fr5g",
        "discovery": "UNKNOWN"
      },
      "title": "GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-64655",
    "datePublished": "2026-08-06T18:41:54.628Z",
    "dateReserved": "2026-07-20T17:11:30.896Z",
    "dateUpdated": "2026-08-08T02:23:17.134Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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