GitHub CLI (gh) Vulnerability: Regex Bypass in Attestation Verification
Summary
DEBIAN-CVE-2026-64655: GitHub CLI (gh) is GitHub’s official command line tool. Affects gh versions 2.23.0+dfsg1-1 – 2.46.0-4. No fix is published. How to fix ↓
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Background
GitHub CLI (gh) is the official command line tool for interacting with GitHub, enabling users to manage repositories, pull requests, issues, and more directly from the terminal. It is widely used in CI/CD pipelines for automating workflows. However, prior to version 2.97.0, it had a significant vulnerability that allowed attackers to exploit the way it handled repository and workflow names during attestation verification.
Vulnerability Detail
The vulnerability arises from the 'gh attestation verify' command, which constructs the certificate Subject Alternative Name matcher using user-supplied values from the --signer-repo and --signer-workflow flags without properly escaping regex metacharacters. This oversight allows an attacker to create a lookalike repository name that matches the intended signer, thereby bypassing the Sigstore attestation verification process. This could lead to serious implications for supply chain security, as it undermines the trust model in CI/CD pipelines and policy gates that rely on specific signing workflows.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, avoid using the 'gh attestation verify' command with untrusted or unknown repository and workflow names until you can update to the patched version.
Conclusion
In summary, the GitHub CLI (gh) vulnerability allows for regex bypass in attestation verification, posing a risk to supply chain security. Users are advised to update to version 2.97.0 or later to mitigate this risk and can utilize Vulert for ongoing vulnerability monitoring.
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FAQ
The vulnerability allows attackers to bypass attestation verification, potentially undermining the security of CI/CD pipelines.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Versions of GitHub CLI prior to 2.97.0 are affected by this vulnerability.
Yes, avoid using the 'gh attestation verify' command with untrusted names until you can update to the patched version.
Vulert monitors and alerts for open-source vulnerabilities in your software using just a manifest file like package-lock.json, providing real-time insights.
References
Related vulnerabilities
Recent vulnerabilities recorded for gh.
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