CVE-2026-93606 vm2 before 3.12.1 Sandbox Escape via Promise Symbol.species
Sandboxed code can escape the vm2 sandbox and execute arbitrary code on the host by exploiting Promise Symbol.species handling.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-93606?
CVE-2026-93606 is a critical code injection vulnerability in patriksimek vm2, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
vm2 (npm) versions 3.12.0 and earlier contain a sandbox escape in `VM` and `NodeVM`. When an embedder exposes a host API that returns a host-realm Promise, the bridge's rejection sanitizer (hostPromiseSanitizeReject / makeSanitizedPromiseCallback / normalizeHostPromiseCallbacks in lib/bridge.js) only wraps `then`/`catch` rejection slots that hold a function, and the sandbox-side `Symbol.species`/`.then` neutralization is installed only on the sandbox intrinsic `Promise.prototype`, so it never applies to a host Promise. Code running inside the sandbox can overwrite `p.constructor[Symbol.species]` on the host Promise and then call `p.then()` with no `onRejected` handler; V8 substitutes its internal Thrower, which re-throws the raw host rejection value into a resolve/reject closure captured by the attacker. This delivers an unsanitized, fully functional bridge proxy of the host object to sandboxed code, bypassing handleException and hostPromiseSanitizeReject. If the rejection value is host-pivotable (for example a host `process` object), this results in arbitrary code execution on the host. Fixed in 3.12.1.
Weakness: CWE-693
Which versions are affected by CVE-2026-93606?
How do I fix CVE-2026-93606?
No fix has been published for CVE-2026-93606 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-93606 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93606 exists.
Sources
Also known as GHSA-6454-5x88-m6jw, GHSA-q84h-7qfg-c6j8.