CVE-2026-86083: Sandbox Escape and Remote Code Execution via Code-Printer Injection in n8n Legacy Expression Engine
Vulnerability ID: CVE-2026-86083
CVSS Score: 7.7
Published: 2026-09-10
A critical sandbox escape vulnerability exists in the legacy expression engine of n8n. By leveraging Shared Builtin Tampering combined with Code-Printer Injection, an authenticated attacker can hijack the mutable global JSON.stringify function. This hijacking allows the attacker to inject arbitrary Node.js source code into internal execution contexts during code generation, escaping the isolated-vm sandbox and achieving full remote code execution on the host system.
TL;DR
An authenticated user can bypass the isolated-vm sandbox in n8n's legacy expression engine by poisoning the global JSON.stringify function, leading to arbitrary host command execution.
⚠️ Exploit Status: POC
Technical Details
- CWE ID: CWE-94
- Attack Vector: Network
- CVSS v4.0 Score: 7.7
- Exploit Status: PoC Available
- KEV Status: Not Listed
Affected Systems
- n8n open-source workflow automation platform using legacy expression engine
-
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 to version 1.123.76, 2.37.7, 2.38.2 or later
- Configure N8N_EXPRESSION_ENGINE environment variable to 'vm'
- Employ non-root container isolation for the n8n process
Remediation Steps:
- Identify the current n8n version in deployment
- Deploy the appropriate patch release from n8n's official distribution channel
- Alternatively, export the environment variable N8N_EXPRESSION_ENGINE=vm in the deployment configuration
- Restart the n8n container or service daemon to apply the configuration
- Verify that legacy expression engine warnings are no longer logged
References
Read the full report for CVE-2026-86083 on our website for more details including interactive diagrams and full exploit analysis.
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