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Fencer Intel
medium 5.9

CVE-2026-77083 json

n8n before 1.123.69 Code Node Sandbox Escape via Function.prototype Pollution

published 3mo ago modified 2mo ago also EUVD-2026-63271 , GHSA-c9c6-rq46-h25v

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository n8n-io/n8n. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.9
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

n8n is a workflow automation platform. In versions prior to 1.123.69, 2.33.4, and 2.34.1, the JavaScript Code node's VM sandbox did not freeze the sandbox's Function.prototype, allowing an authenticated user with the ability to create and execute workflows to pollute it from within a Code node execution and recover a reference to the host's globalThis, resulting in a sandbox escape. The full exploit chain additionally depends on specific modules being available as allowlisted imports in the deployment's configuration. The issue is fixed in versions 1.123.69, 2.33.4, and 2.34.1.

Patch / fix

  • npm n8n >= 1.123.69, >= 2.33.4, >= 2.34.1
  • n8n-io n8n 1.123.69, 2.33.4, 2.34.1

Is CVE-2026-77083 in your dependencies? 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
none
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 4.0 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm n8n
<1.123.69
<2.34.1
<2.33.4
>= 1.123.69
>= 2.34.1
>= 2.33.4

Affected products

  • n8n-io n8n

Classification

Weakness
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

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.

The maintainers of n8n-io/n8n published their own advisory on GitHub. Reviewed sources take precedence over it.