GHSA-8hq7-ggx2-cc6m

Suggest an improvement
Source
https://github.com/advisories/GHSA-8hq7-ggx2-cc6m
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-8hq7-ggx2-cc6m/GHSA-8hq7-ggx2-cc6m.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-8hq7-ggx2-cc6m
Aliases
Published
2026-10-08T17:39:57Z
Modified
2026-10-08T18:00:08Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L CVSS Calculator
Summary
msgpack5: Partial options disable prototype protection
Details

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.

Database specific 
{
    "cwe_ids": [
        "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-08T17:39:57Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
}
References

Affected packages

npm / msgpack5

Package

Name
msgpack5
View open source insights on deps.dev
Purl
pkg:npm/msgpack5

Affected ranges

Type
SEMVER
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
6.1.0

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-8hq7-ggx2-cc6m/GHSA-8hq7-ggx2-cc6m.json"