WS-2026-0144
Published:October 08, 2026
Updated:October 22, 2026
@payloadcms/plugin-mcp 3.64.0 through 3.87.1 (and four 4.0.0-internal builds from May 2026): an operator-precedence bug in the default MCP API-key resolver made it ignore the key passed by a custom overrideAuth function and authenticate with the request's Authorization bearer header instead, so custom MCP authentication did not restrict access as configured (GHSA-cqr4-hjg9-833p)
Affected Packages
https://github.com/payloadcms/payload.git (GITHUB):
Affected version(s) >=v3.64.0 <v3.88.0Fix Suggestion:
Update to version v3.88.0@payloadcms/plugin-mcp (NPM):
Affected version(s) >=3.65.0 <3.88.0Fix Suggestion:
Update to version 3.88.0Related Resources (3)
Do you need more information?
Contact UsCVSS v4
Base Score:
7.6
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.8
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Authentication