CVE-2026-42234: 
NixOS vulnerability analysis and mitigation

CVE-2026-42234 is a Python Task Runner sandbox escape vulnerability in n8n, an open-source workflow automation platform. An authenticated user with permission to create or modify workflows containing a Python Code Node can escape the sandbox and achieve arbitrary code execution on the task runner container. The vulnerability was first published on April 22, 2026, and affects n8n versions prior to 1.123.32, versions 2.17.0–2.17.3, and version 2.18.0. It carries a CVSS v4.0 base score of 7.1 (High) and a CVSS v3.1 base score of 8.8 (High) (GitHub Advisory, n8n Security Advisory).

The root cause is classified as CWE-94 (Improper Control of Generation of Code / Code Injection): the Python Code Node does not sufficiently neutralize user-supplied input, allowing it to break out of the intended sandbox environment. The attack vector is network-based, requires low privileges (an authenticated account with workflow creation/modification rights), and no user interaction beyond the attacker's own actions. Exploitation is conditional on the Python Task Runner being enabled in the n8n instance. The vulnerability was reported by researcher 'dorjoos' (GitHub Advisory, n8n Security Advisory).

Successful exploitation allows an authenticated attacker to execute arbitrary code on the task runner container, resulting in high confidentiality impact (access to sensitive data processed by the container), low integrity impact (unauthorized modification of system data), and no direct availability impact per the CVSS v4.0 assessment. The scope is limited to the task runner container itself, but depending on the deployment architecture, this could enable lateral movement to other services or data stores accessible from that container (GitHub Advisory, n8n Security Advisory).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (GitHub Advisory). The EPSS score is approximately 0.07–0.095% (26th percentile), indicating a low near-term exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been reported.

1. Reconnaissance: Identify n8n instances (version < 1.123.32, 2.17.0–2.17.3, or 2.18.0) with the Python Task Runner enabled, using network scanning or service fingerprinting tools.
2. Authentication: Obtain or use existing low-privileged credentials for an account that has permission to create or modify workflows in the target n8n instance.
3. Workflow creation: Log in to the n8n web interface and create a new workflow (or modify an existing one) that includes a Python Code Node.
4. Sandbox escape payload: Insert a crafted Python code payload into the Python Code Node that exploits the insufficient sandbox restrictions — for example, using Python built-ins or module imports (e.g., os, subprocess) to execute system commands outside the intended sandbox boundary.
5. Trigger execution: Save and execute the workflow to cause the n8n Python Task Runner to evaluate the malicious code, achieving arbitrary command execution on the task runner container.
6. Post-exploitation: Use the code execution foothold to exfiltrate sensitive data, establish persistence, or pivot to other services accessible from the container (GitHub Advisory, n8n Security Advisory).

• Logs: n8n workflow execution logs showing Python Code Node executions by non-administrative users; unexpected system-level commands or errors appearing in task runner container logs.
• Process: Unusual child processes spawned by the n8n Python task runner process (e.g., sh, bash, curl, wget, python3 with unexpected arguments); processes making outbound network connections from the task runner container.
• Network: Unexpected outbound connections from the task runner container to external IP addresses or internal services not normally accessed during workflow execution.
• File System: New or modified files in the task runner container's filesystem, particularly scripts, binaries, or configuration files created outside of normal n8n operation; presence of reverse shell scripts or downloaded payloads.

Upgrade n8n to one of the patched versions: 1.123.32, 2.17.4, or 2.18.1 (or later). If immediate upgrade is not possible, administrators should apply the following temporary mitigations: (1) restrict workflow creation and editing permissions to fully trusted users only; (2) disable the Python Code node by adding n8n-nodes-base.code to the NODES_EXCLUDE environment variable; or (3) disable the Python Task Runner entirely. Note that these workarounds do not fully remediate the risk and are intended only as short-term measures (GitHub Advisory, n8n Security Advisory).

The vulnerability was detected by Qualys (detection ID 531330) and included in their May 2026 application security detections publication. A brief technical write-up was published by Infinitsec shortly after disclosure. No significant broader media coverage or notable researcher commentary beyond the initial advisory has been identified (GitHub Advisory).