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

unknownCVE-2026-64655

CSIRTS triage

vendor: GitHub product: GitHub CLI Authentication bypass

What: Attestation verification can be bypassed via unescaped regex metacharacters in Subject Alternative Name matching.
Who is affected: GitHub CLI users relying on attestation verification.
Urgency: Severity unknown but auth-bypass is critical in nature; investigate and patch immediately.
Action: Upgrade GitHub CLI to the patched version addressing CVE-2026-64655.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64655

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-646550.32% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 25% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-64655	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownCVE-2026-64655: GitHub CLI (gh) is GitHub’s official command line tool. Prior to 2.97.0, gh attestation verify…nvd

Recent advisories for GitHub CLI

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

unknownCVE-2026-72924: GitHub CLI (gh) is GitHub's official command line tool. Versions 2.28.0 through 2.97.0 bind th…nvd · 2026-08-25
unknownCVE-2026-64654: GitHub CLI: Terminal escape sequence injection in multiple `gh` commandsmsrc · 2026-08-11
unknownCVE-2026-64653: GitHub CLI: Unescaped variable components in request URLs could allow path traversalmsrc · 2026-08-11
lowCVE-2026-64652: GitHub CLI: Partial token disclosure in `gh auth status` outputmsrc · 2026-08-11
unknownCVE-2026-64655: GitHub CLI (gh) is GitHub’s official command line tool. Prior to 2.97.0, gh attestation verify…nvd · 2026-08-06
unknownCVE-2026-64654: GitHub CLI (gh) is GitHub's official command line tool. Prior to version 2.97.0, multiple GitH…nvd · 2026-08-06