CVE intelligence

CVE-2026-64655

Vulnerability intelligence

Published Aug 6, 2026Sources checked Oct 28, 2026

2.1LOWCVSS out of 10

What this means

Review the available evidence

CVE-2026-64655 and is rated Low severity with a CVSS score of 2.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Aug 23, 2026

CBL-Mariner Releases

Vendor-listed releases

2.97.0-1

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-64655?

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.

Source: NVD