An attacker can subvert n8n's Python task executor sandbox by exploiting string formatting in exception handling, enabling arbitrary Python code to run with privileges of the underlying operating system. The vulnerability is triggered through the built‑in Code block node by an authenticated user with basic permissions and can grant full control over an n8n instance when it operates in its default internal execution mode.

All deployments of the n8n workflow automation platform that include the built‑in Code block node, regardless of execution mode. The issue applies to n8n running on Node.js environments and is present in the versions that have not yet incorporated the commit that removes the sandbox vulnerability.

The vulnerability scores a high CVSS 8.5 and an EPSS of less than 1%, indicating a technically severe flaw but a presently low probability of exploitation. It is not listed in the CISA KEV catalog. An attacker requires authenticated access to create or edit a Code block and can then trigger the sandbox escape, leading to arbitrary code execution in the underlying host on Internal execution mode, or restricted execution within a Sidecar container on External execution mode. The impact thus varies with configuration but remains significant, especially in Internal mode.