[ CVE-2026-92942 · Published 17 Sep 2026 ]
vm2: timeout Option Bypass via FinalizationRegistry Cleanup Callback (Unbounded Host Event-Loop Block)
[ Why it matters ]Priority signals
- Public proof-of-concept exploit exists (CISA SSVC)
[ Description ]Official description
vm2 before 3.11.7 (affected versions <= 3.11.6) does not enforce the VM({ timeout }) option on code executed outside the synchronous VM#run() call. The timeout only wraps the single call to _runScript() via doWithTimeout() in lib/vm.js, and FinalizationRegistry and WeakRef are exposed to sandboxed code unmodified (they are not among the hardened globals in lib/setup-sandbox.js). Sandboxed code can register a FinalizationRegistry cleanup callback against an object and then drop the only strong reference to it; vm.run() returns within the configured timeout, but when the V8 garbage collector later reclaims the object it invokes the sandboxed cleanup callback outside any vm2 timeout accounting. A busy loop in that callback blocks the host event loop for an unbounded period, resulting in denial of service. The time of invocation depends on the garbage collector (e.g. under memory pressure or with --expose-gc).
[ Fixes ]Fixes and patches
- vm2 3.11.7Fixed version · GitHub Advisories · npm package vm2: upgrade to 3.11.7 or later (affected <= 3.11.6)
[ Packages ]Affected open-source packages
- vm2 npmAffected <= 3.11.6 · fixed in 3.11.7 · GHSA-r4fx-v8hh-22mv