{"id":"CVE-2026-107301","aliases":["AZL-106857","CLSA-2026-1793302953","EUVD-2026-95112","GHSA-8hq7-ggx2-cc6m"],"status":"published","title":"msgpack5: Partial options disable prototype protection","description":"msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00366,"percentile":0.30853,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-10-08T17:13:00Z","modified":"2026-10-30T02:15:06Z","fixes":[{"ecosystem":"npm","package":"msgpack5","fixed_in":["6.1.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"msgpack5","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.0"}]}]},{"source":"osv","ecosystem":"Azure Linux:3","package":"msgpack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"3.3.0-1"}]}]},{"source":"osv","ecosystem":"TuxCare:npm","package":"msgpack5","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.6.1-tuxcare.0"},{"fixed":"3.6.1-tuxcare.1"}]}],"versions":["3.6.1"],"bundled":7},{"source":"osv","ecosystem":"npm","package":"msgpack5","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"6.1.0"}]}]}],"products":[{"vendor":"mcollina","product":"msgpack5"}],"references":[{"url":"https://github.com/mcollina/msgpack5/security/advisories/GHSA-8hq7-ggx2-cc6m","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/mcollina/msgpack5/commit/20e82600ac9462e679c8a45e5723315f21e2c774","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/mcollina/msgpack5/releases/tag/v6.1.0","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-8hq7-ggx2-cc6m"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107301","tags":["web","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107301.json","tags":["advisory"]},{"url":"https://github.com/mcollina/msgpack5","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-107301","title":"msgpack5: Partial options disable prototype protection","description":"msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.","status":"published","published":"2026-10-08T17:13:00.613Z","modified":"2026-10-14T01:02:53.277Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T13:45:14.072357Z"}],"euvd":[{"id":"EUVD-2026-95112","description":"msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.","status":"published","published":"2026-10-08T17:13:00Z","modified":"2026-10-14T01:02:53Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium"}],"updated_at":"2026-11-02T17:27:18.393051Z"}],"ghsa":[{"id":"GHSA-8hq7-ggx2-cc6m","title":"msgpack5: Partial options disable prototype protection","description":"### Impact\n\nPassing 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.\n\nOnly the decoded object's prototype is affected; this does not modify `Object.prototype` globally.\n\n### Patches\n\nOptions are now merged with secure defaults without modifying the caller's object. Unsupported `protoAction` values are rejected.\n\n### Workarounds\n\nExplicitly set `protoAction: 'error'` whenever constructing a msgpack5 instance, and validate decoded values before use.","status":"published","published":"2026-10-08T17:39:57Z","modified":"2026-10-08T17:39:58Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:41:30.097746Z"}],"nvd":[{"id":"CVE-2026-107301","description":"msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.","status":"published","published":"2026-10-08T17:17:16.143Z","modified":"2026-10-14T01:17:05.583Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium","assessor":"secondary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:12:55.142936Z"}],"osv":[{"id":"CVE-2026-107301","title":"msgpack5: Partial options disable prototype protection","description":"msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.","status":"published","published":"2026-10-08T17:13:00.613Z","modified":"2026-10-28T02:30:24.17777313Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:44:54.933106Z"},{"id":"GHSA-8hq7-ggx2-cc6m","title":"msgpack5: Partial options disable prototype protection","description":"### Impact\n\nPassing 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.\n\nOnly the decoded object's prototype is affected; this does not modify `Object.prototype` globally.\n\n### Patches\n\nOptions are now merged with secure defaults without modifying the caller's object. Unsupported `protoAction` values are rejected.\n\n### Workarounds\n\nExplicitly set `protoAction: 'error'` whenever constructing a msgpack5 instance, and validate decoded values before use.","status":"published","published":"2026-10-08T17:39:57Z","modified":"2026-10-08T18:00:08.899286917Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:42.437513Z"},{"id":"AZL-106857","title":"CVE-2026-107301 affecting package msgpack 3.3.0-1","description":"msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, constructing msgpack5 with an empty or partial options object disables the default protoAction: 'error' protection. A decoded map containing a __proto__ key can then replace the decoded object's prototype, potentially changing inherited properties or downstream behavior, although Object.prototype is not modified globally. This issue is fixed in version 6.1.0.","status":"published","published":"2026-10-08T17:17:16Z","modified":"2026-10-15T05:37:09Z","updated_at":"2026-11-02T15:28:01.408755Z"},{"id":"CLSA-2026-1793302953","title":"TuxCare security update for msgpack5 (7 CVEs)","description":"TuxCare rebuilt msgpack5 to address 7 CVEs. Fixed in 3.6.1-tuxcare.1.","status":"published","published":"2026-10-29T20:42:34Z","modified":"2026-10-30T02:15:06.130856267Z","updated_at":"2026-11-02T15:43:55.669514Z"}]}}