Skip to content
Fencer Intel
high 8.5

CVE-2026-0863 json

Sandbox escape in n8n Python task runner allows for arbitrary code execution on the underlying host.

published 9mo ago modified 4mo ago also EUVD-2026-3171

cvss
8.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
9.3%
EPSS 9.3% chance of exploitation in 30 days, percentile 95%
public exploits
0
none known

Summary

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.

Patch / fix

  • n8n n8n 1.123.14, 2.3.5, 2.4.2

Is CVE-2026-0863 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
9mo ago

Exploit prediction

9.29% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • research.jfrog.com https://research.jfrog.com/vulnerabilities/n8n-python-runner-sandbox-escape-jfsa-2026-001651077/ referenced PoC, tagged "exploit" by a source, unverified
  • smartkeyss.com https://www.smartkeyss.com/post/cve-2026-0863-python-sandbox-escape-in-n8n-via-exception-formatting-and-implicit-code-execution referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Classification

Weakness
  • CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.