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Luu, T.J.

GHSA-6xcw-7xm6-48c6: n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code Execution

highvulnerability

security

Source: GitHub Advisory DatabaseSeptember 10, 2026CVE-2026-86083

Summary

n8n, a workflow automation platform, had a vulnerability in its legacy expression engine where attackers could escape the expression sandbox (a restricted environment meant to safely execute code) by tampering with the global JSON.stringify function. This allowed them to turn data into executable code and gain full code execution. The default vm expression engine is not affected by this issue.

Solution / Mitigation

The issue has been fixed in n8n versions 1.123.76, 2.37.7, and 2.38.2. Users should upgrade to one of these versions or later. If upgrading is not immediately possible, administrators can: set the environment variable N8N_EXPRESSION_ENGINE=vm to switch to the vm expression engine (which is not affected), restrict n8n instance access to fully trusted users only, or ensure the n8n process runs under a dedicated low-privilege OS user account to limit the impact of any command execution. The source notes these workarounds do not fully remediate the risk and should only be used as short-term measures.