Prototype pollution in n8n - #VU153001
Published: September 30, 2026
Vulnerability identifier: #VU153001
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-1321
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to take over the instance owner's account.
The vulnerability exists due to improper control of object prototype attributes in the MCP workflow-validation interpreter when evaluating caller-supplied code. A remote user can replace a built-in method with one that returns a truthy value to bypass a server-side permission check and take over the instance owner's account.
Accounts protected by MFA are not affected.
Affected software
n8n
Remediation
Install security update from vendor's website.
n8n - addressed in versions 2.41.4, 2.42.1