n8n: Python Code Node AST Validator Bypass

Impact

An authenticated user with permission to create or modify workflows containing a Python Code node could bypass the AST security validator and access the task executor module namespace. On self-hosted instances where N8N_BLOCK_RUNNER_ENV_ACCESS=false is set, this extended to disclosure of environment variables accessible to the task runner process.

This issue only affects instances where the Python Task Runner is enabled and N8N_BLOCK_RUNNER_ENV_ACCESS=true.

Patches

The issue has been fixed in n8n versions 2.25.7, and 2.26.2. 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:

• Limit workflow creation and editing permissions to fully trusted users only.
• Disable the Python Code node by adding n8n-nodes-base.code to the NODES_EXCLUDE environment variable, or disable the Python Task Runner entirely.

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