CVE-2026-86076: Remote Code Execution via Expression Sandbox Escape in n8n
Vulnerability ID: CVE-2026-86076
CVSS Score: 8.7
Published: 2026-09-10
An expression sandbox escape vulnerability exists in n8n due to a missing AST traversal check on ClassBody in the PrototypeSanitizer. This allows authenticated users with low privileges to bypass property checks and achieve remote code execution.
TL;DR
A missing ClassBody traversal in n8n's expression sanitizer allows low-privileged users to redefine the '__sanitize' resolver on custom classes, escaping the sandbox to execute arbitrary Node.js commands.
Technical Details
- CWE ID: CWE-94
- Attack Vector: Network
- CVSS Score: 8.7 (High)
- Impact: Remote Code Execution (RCE) / Stored Cross-User JavaScript Execution
- Exploit Status: PoC (Proof of Concept) Feasible
- KEV Status: Not Listed
Affected Systems
- n8n Workflow Automation Platform
-
n8n: < 1.123.76 (Fixed in:
1.123.76) -
n8n: >= 2.0.0, < 2.37.7 (Fixed in:
2.37.7) -
n8n: >= 2.38.0, < 2.38.2 (Fixed in:
2.38.2)
Mitigation Strategies
- Upgrade n8n immediately to version 1.123.76, 2.37.7, or 2.38.2 to resolve the missing AST check.
- Audit stored workflow configurations within the system database to identify unauthorized expressions.
- Enforce strict Role-Based Access Control (RBAC) to ensure untrusted users cannot author workflows.
Remediation Steps:
- Locate the active deployment and execute the version bump (e.g., 'docker pull n8n-io/n8n:2.38.2').
- Scan the workflow database using SQL queries for occurrence of '__sanitize' within the workflow definitions.
- Restrict workspace configuration and editing privileges to administrative roles.
References
- n8n Security Advisory GHSA-hw8v-xxg5-vvvx
- n8n Release 1.123.76
- n8n Release 2.37.7
- n8n Release 2.38.2
Read the full report for CVE-2026-86076 on our website for more details including interactive diagrams and full exploit analysis.
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