CVE-2026-42236
Published:May 04, 2026
Updated:June 25, 2026
n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, the MCP OAuth client registration endpoint accepted unauthenticated requests and stored client data without adequate resource controls. An unauthenticated remote attacker could exhaust server memory resources by sending large registration payloads, rendering the n8n instance unavailable. The MCP enable/disable toggle gates MCP access but did not restrict client registrations, meaning the endpoint is reachable regardless of whether MCP access is enabled on the instance. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.
Affected Packages
n8n (NPM):
Affected version(s) >=0.0.1 <2.18.1Fix Suggestion:
Update to version 2.18.1n8n (NPM):
Affected version(s) >=0.0.1 <1.123.32Fix Suggestion:
Update to version 1.123.32n8n (NPM):
Affected version(s) >=0.0.1 <2.17.4Fix Suggestion:
Update to version 2.17.4n8n (NPM):
Affected version(s) >=0.0.1 <1.123.32Fix Suggestion:
Update to version 1.123.32n8n (NPM):
Affected version(s) >=2.0.0 <2.17.4Fix Suggestion:
Update to version 2.17.4n8n (NPM):
Affected version(s) =2.18.0 <2.18.1Fix Suggestion:
Update to version 2.18.1Related Resources (3)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Allocation of Resources Without Limits or Throttling
EPSS
Base Score:
0.49