# CVE-2026-64655: GitHub CLI: Attestation Verification Bypass via Unescaped Regex Metacharacters in SAN Matching

> Attackers can bypass GitHub CLI attestation verification by using regex metacharacters in signer names, undermining supply chain security for CI/CD pipelines.

- **Severity:** Low 2.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 6 Aug 2026
- **Updated:** 8 Aug 2026
- **Also known as:** AZL-95472, DEBIAN-CVE-2026-64655, GHSA-mm27-mwq9-fr5g, GO-2026-6767, MINI-2q9m-9fv3-75r5, MINI-6vrj-m5jq-28jp, UBUNTU-CVE-2026-64655

## What is CVE-2026-64655?

CVE-2026-64655 is a low-severity vulnerability in cli, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-185 (Incorrect Regular Expression)

## Which versions are affected by CVE-2026-64655?

4 open source packages ship an affected version, including github.com/cli/cli/v2 and github.com/cli/cli.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/cli/cli/v2` | Go | All versions | 2.97.0 |
| `github.com/cli/cli/v2` | Go | All versions | 2.97.0 |
| `github.com/cli/cli/v2` | Go | All versions | 2.97.0 |
| `github.com/cli/cli` | Go | All versions | None |

## How do I fix CVE-2026-64655?

Upgrade github.com/cli/cli/v2 to 2.97.0 or later.

## Is CVE-2026-64655 being exploited?

There is no known exploitation of CVE-2026-64655 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64655 and fix it if it is affected.

What it is: CVE-2026-64655 is a low-severity vulnerability in cli, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-64655 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/cli/cli/v2 (Go): affected all versions; fixed in 2.97.0
- github.com/cli/cli/v2 (Go): affected all versions; fixed in 2.97.0
- github.com/cli/cli/v2 (Go): affected all versions; fixed in 2.97.0
- github.com/cli/cli (Go): affected all versions; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-64655/ (Markdown: https://insights.sbomify.com/CVE-2026-64655/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64655
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64655
- OSV: https://osv.dev/vulnerability/CVE-2026-64655

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64655/
Summaries are generated and may contain mistakes; the official description above is the record.