CVE-2026-86076: n8n: Expression Sandbox Escape in Editor-UI Enables Stored Cross-User JavaScript Execution

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-08 · updated 2026-09-11
Weakness: CWE-94

Description

n8n is an open source workflow automation platform. Prior to 1.123.76, 2.37.7, and 2.38.2, the expression compiler sanitizer resolved through dynamically scoped this and did not reject reserved class member names. A class field named __sanitize could rebind the sanitizer and reach the Function constructor, enabling backend code execution and editor-preview JavaScript execution. The affected AST hook is PrototypeSanitizer in packages/workflow/src/expression-sandboxing.ts. This issue is fixed in versions 1.123.76, 2.37.7 and 2.38.2.

Affected products

n8n-io n8n: before 1.123.76; from 2.0.0 before 2.37.7; from 2.38.0 before 2.38.2 — fixed in 1.123.76, 2.37.7, 2.38.2

How to fix

Upgrade to a fixed version: n8n-io n8n 1.123.76, 2.37.7, 2.38.2. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-86076 or the next vulnerability affects your stack