How severe is GHSA-8hq7-ggx2-cc6m?

GHSA-8hq7-ggx2-cc6m has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-8hq7-ggx2-cc6m?

GHSA-8hq7-ggx2-cc6m affects the following packages: msgpack5 (npm). Ecosystems affected: npm.

How do I fix GHSA-8hq7-ggx2-cc6m?

Update msgpack5 to 6.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8hq7-ggx2-cc6m is resolved across your whole dependency graph.

How do I detect GHSA-8hq7-ggx2-cc6m in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for msgpack5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-8hq7-ggx2-cc6m if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is GHSA-8hq7-ggx2-cc6m actively exploited in the wild?

No public exploit code has been indexed for GHSA-8hq7-ggx2-cc6m yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-8hq7-ggx2-cc6m?

GHSA-8hq7-ggx2-cc6m has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 29th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-8hq7-ggx2-cc6m?

GHSA-8hq7-ggx2-cc6m is classified as CWE-1321 (CWE-1321). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-8hq7-ggx2-cc6m published, and has it been updated?

GHSA-8hq7-ggx2-cc6m was published on October 8, 2026 and was last updated on October 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

msgpack5: Partial options disable prototype protectionGHSA-8hq7-ggx2-cc6m

MEDIUMFix: mcollina/msgpack5@20e8260

GHSA-8hq7-ggx2-cc6m is a medium-severity (CVSS 6.5) CWE-1321 vulnerability in msgpack5. A fix is available for msgpack5 — see the affected versions and patch details below.

Also known asCVE-2026-107301

Published

Oct 8, 2026

Updated

Oct 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-8hq7-ggx2-cc6m.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-8hq7-ggx2-cc6m by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

214other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

msgpack5npm

89Kdownloads / week

Description

Impact

Passing an empty or partial options object disables the default protoAction: 'error' protection. A map containing a __proto__ key can then replace the prototype of the decoded object, potentially changing inherited properties or causing unexpected behavior in downstream code.

Only the decoded object's prototype is affected; this does not modify Object.prototype globally.

Patches

Options are now merged with secure defaults without modifying the caller's object. Unsupported protoAction values are rejected.

Workarounds

Explicitly set protoAction: 'error' whenever constructing a msgpack5 instance, and validate decoded values before use.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`msgpack5`	all versions	6.1.0`npm install msgpack5@6.1.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for msgpack5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update msgpack5 to 6.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8hq7-ggx2-cc6m is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact Passing an empty or partial options object disables the default `protoAction: 'error'` protection. A map containing a `__proto__` key can then replace the prototype of the decoded object, potentially changing inherited properties or causing unexpected behavior in downstream code. Only the decoded object's prototype is affected; this does not modify `Object.prototype` globally. ### Patches Options are now merged with secure defaults without modifying the caller's object. Unsupported `protoAction` values are rejected. ### Workarounds Explicitly set `protoAction: 'error'` wheneve