n8n: Legacy Expression Evaluator Sanitizer Bypass Leads to Authenticated Code Execution

Impact

The legacy expression evaluator's computed-member sanitizer can be bypassed by an authenticated user with workflow create or modify permissions. Successful exploitation grants the attacker host-level code execution as the n8n process.

The legacy expression engine is the default engine in affected versions.

Patches

The issue has been fixed in n8n versions 1.123.64, 2.29.8, and 2.30.1. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

• Restrict n8n instance access to fully trusted users only.
• Switch to the non-legacy expression engine by setting N8N_EXPRESSION_ENGINE=vm.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.