# CVE-2026-64655: GitHub CLI attestation verification regex bypass

Source: https://junglewise.ai/threats/cve-2026-64655-github-cli-attestation-verification-regex-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-06. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-64655 · Severity: medium · CVSS 4 · Published 2026-08-06

GitHub CLI is the official command-line tool for interacting with GitHub. The `gh attestation verify` command failed to properly escape regex metacharacters when validating Sigstore attestations against trusted signing workflows, allowing an attacker to register a lookalike repository (e.g., `github/artifact.attestations-workflows` instead of `github/artifact-attestations-workflows`) that would pass verification. This could let an attacker inject malicious code into CI/CD pipelines or bypass supply chain security policies that rely on attestation verification.

Technologies: [github.com/cli/cli (Go)](https://junglewise.ai/threats/technologies/github-com-cli-cli), [github.com/cli/cli/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-cli-cli-v2). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-64655 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-64655 being exploited in the wild.

**How severe is CVE-2026-64655?** Medium severity, with a CVSS score of 4, published 6 August 2026.

**Which products and versions are affected?** github.com/cli/cli (Go) SEMVER:introduced=0; github.com/cli/cli/v2 (Go) < 2.97.0, SEMVER:introduced=0,fixed=2.97.0.

**Is there a fix for CVE-2026-64655?** Yes. github.com/cli/cli/v2 (Go): upgrade to 2.97.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-64655 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-64655?** Check whether you run github.com/cli/cli (Go) or github.com/cli/cli/v2 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/cli/cli/v2 (Go): upgrade to 2.97.0 or later

  ```sh
  go get github.com/cli/cli/v2@v2.97.0
  ```


## Technical details

The vulnerability is a regex injection flaw in the `gh attestation verify` command. When the `--signer-repo` and `--signer-workflow` flags are used to specify a trusted signer, the tool constructs a certificate Subject Alternative Name matcher without escaping regex metacharacters. Characters like `.` that are valid in GitHub organization, repository, and workflow names are regex wildcards, allowing an attacker to craft a repository name that matches a different intended signer. Exploitation requires creating a plausible lookalike repository and generating valid Sigstore attestations from it. The attack vector is network-based, requiring no authentication or special user interaction beyond the user running the verify command. The fix was applied in version 2.97.0 by properly escaping the metacharacters.

## Affected products

- GitHub CLI before 2.97.0

## Identifiers

- CVE-2026-64655
- GHSA-mm27-mwq9-fr5g
- GO-2026-6767

## Timeline

- 2026-08-06: disclosed
- 2026-07-31: patched: Fixed in version 2.97.0

## References

- [https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55](https://github.com/cli/cli/commit/55dbb4dc6b7edb10b48e3d7fc5bccd32318d1b55)
- [https://github.com/cli/cli/releases/tag/v2.97.0](https://github.com/cli/cli/releases/tag/v2.97.0)

## Related threats

- [GitHub CLI path traversal via unescaped URL components](https://junglewise.ai/threats/cve-2026-64653-github-cli-path-traversal-via-unescaped-url-components)
- [GitHub CLI token masking bypass in auth status](https://junglewise.ai/threats/cve-2026-64652-github-cli-token-masking-bypass-in-auth-status)
- [GitHub CLI incorrect authorization header in attestation and release commands](https://junglewise.ai/threats/cve-2026-48501-github-cli-incorrect-authorization-header-in-attestation-and)
- [GitHub CLI terminal escape sequence injection in gh run view](https://junglewise.ai/threats/cve-2026-45803-github-cli-terminal-escape-sequence-injection-in-gh-run-view)
- [`gh attestation verify` returns incorrect exit code during verification if no attestations are present](https://junglewise.ai/threats/cve-2025-25204-gh-attestation-verify-returns-incorrect-exit-code-during)