CVE-2026-107301
Published:October 08, 2026
Updated:October 09, 2026
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.
Affected Packages
msgpack5 (CDN_JS):
Affected version(s) >=6.0.0 <6.1.0Fix Suggestion:
Update to version 6.1.0https://github.com/mcollina/msgpack5.git (GITHUB):
Affected version(s) >=v6.0.0 <v6.1.0Fix Suggestion:
Update to version v6.1.0msgpack5 (NPM):
Affected version(s) >=6.0.0 <6.1.0Fix Suggestion:
Update to version 6.1.0Additional Notes
The description of this vulnerability differs from MITRE.
Related Resources (6)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
LOW
Weakness Type (CWE)
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')