Allocation of Resources Without Limits or Throttling in n8n - CVE-2026-42236
Published: April 23, 2026
Vulnerability identifier: #VU127221
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42236
CWE-ID: CWE-770
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper resource control in the MCP OAuth client registration endpoint when handling unauthenticated client registration requests. A remote attacker can send large registration payloads to cause a denial of service.
The endpoint is reachable regardless of whether MCP access is enabled on the instance.
Affected software
n8n
How to mitigate CVE-2026-42236
Install security update from vendor's website.
n8n - addressed in versions 1.123.32, 2.17.4, 2.18.1