---
id: "CVE-2026-64655"
kind: "vulnerability"
aliases: ["CVE-2026-64655", "GHSA-mm27-mwq9-fr5g", "GO-2026-6767"]
title: "GitHub CLI allows attestation verification bypass through unescaped regex metacharacters in github.com/cli/cli"
severity: "low"
cvss: 2.1
epss: 0.00343
exploited: false
status: "open"
category: "package"
products: [{"name": "github.com/cli/cli", "fixed": [], "affected": "all versions", "ecosystem": "go"}, {"name": "github.com/cli/cli/v2", "fixed": ["2.97.0"], "affected": "< 2.97.0", "ecosystem": "go"}]
ecosystems: ["go"]
tags: ["ci-cd", "github-cli", "go", "package", "supply-chain-verification"]
not_affected_if: ["fixed-version-installed", "no-attestation-verify-use"]
published_at: "2026-08-06T22:18:13+00:00"
first_seen_at: "2026-10-23T19:13:08+00:00"
updated_at: "2026-10-23T21:49:27+00:00"
sources: [{"source": "govuln", "url": "https://pkg.go.dev/vuln/GO-2026-6767", "first_seen_at": "2026-10-23T19:13:08+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-64655", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64655", "first_seen_at": "2026-10-23T19:35:23+00:00"}]
---

# GitHub CLI allows attestation verification bypass through unescaped regex metacharacters in github.com/cli/cli

The GitHub CLI's attestation verify command treats the --signer-repo and --signer-workflow values as regular expressions, so a dot in a name matches any character. An attacker who registers a lookalike repository or workflow name can get a signed attestation accepted as coming from a trusted signer.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:github.com/cli/cli affected all versions fixed ?
- go:github.com/cli/cli/v2 affected < 2.97.0 fixed 2.97.0

## How to check

Run gh --version; versions before 2.97.0 are affected. Check CI and policy scripts for gh attestation verify with --signer-repo or --signer-workflow.

## Fix

Upgrade gh to 2.97.0 or later; for the Go module, github.com/cli/cli/v2 at 2.97.0 or later.

## Timeline

- 2026-10-23T19:13:08+00:00 govuln https://pkg.go.dev/vuln/GO-2026-6767
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-64655
- 2026-10-23T19:35:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-64655

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_