CVE-2026-86076: n8n: Expression Sandbox Escape via Class-Field Sanitizer Rebinding Can Lead to Code Execution

The expression compiler’s sanitizer resolved through a dynamically-scoped this, so a class field named __sanitize rebound it and reached the Function constructor. On the backend, any expression author could run code in the n8n process; in the editor preview, a member’s expression could run as JavaScript in the session of whoever opened the workflow. The patch rejects reserved class-member names.