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Fencer Vulns
medium 5.9

CVE-2026-77083 json

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

published 2026-08-20 2 mo ago modified 2026-09-01 2 mo ago also EUVD-2026-63271

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

  • n8n-io n8n 1.123.69, 2.33.4, 2.34.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 products

  • n8n-io n8n

Classification

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

References

Sources

Fencer Vulns 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.