CVE-2026-110842: n8n before 2.41.4 and 2.42.1 Prototype Pollution via MCP Workflow-Validation Interpreter
n8n before 2.41.4 and 2.42.x before 2.42.1 contains a prototype pollution vulnerability in the MCP workflow-validation tool, whose interpreter evaluates caller-supplied code in the main process, reads inherited properties, and permits assignment onto shared prototypes. An authenticated member holding only a workflow:read grant can replace a built-in method with one returning a truthy value so server-side permission checks accept unheld scopes, enabling takeover of owner accounts not protected by MFA.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
n8nto a version that resolves this vulnerability.Fixed in 2.41.4
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated n8n member with only the workflow:read grant can exploit it. The described impact includes taking over owner accounts that are not protected by MFA.
What access or feature is required for exploitation?
The attacker must be able to use the MCP workflow-validation tool with caller-supplied code. The vulnerable interpreter evaluates that code in the main process and allows assignments to shared prototypes.
Which versions are affected?
Affected versions are n8n releases before 2.41.4 and 2.42.x releases before 2.42.1.
How does the issue bypass permissions?
An attacker can replace a built-in method with one that returns a truthy value. This causes server-side permission checks to accept scopes the attacker does not actually hold.