CVE-2026-86083: n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code Execution

Two stages of expression code generation built source text by calling the global JSON.stringify at generation time: the compiler when printing synthetic string literals, and the isolate bridge when interpolating a timezone value into its per-evaluation wrapper. An expression that replaced that global therefore changed the code that was subsequently generated and executed, turning literal data into executable source. The patch renders both code-generation stages through a reference captured at module load, so a later change to global state cannot alter the generated source.

This vulnerability only affects instances running the legacy expression engine. The vm expression engine, which is the default on the patched releases, is not affected.