CVE-2026-47209 vm2: Bridge Proxy set trap ignores receiver parameter, enabling host object property injection via prototype chain
Attackers can inject properties into host objects via prototype chain manipulation, bypassing sandbox restrictions and potentially executing code.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-47209?
CVE-2026-47209 is a high-severity code injection vulnerability in patriksimek vm2, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
vm2 is an open source vm/sandbox for Node.js. Prior to version 3.11.4, the BaseHandler.set trap in bridge.js (line 1231) ignores the receiver parameter and unconditionally writes to the host target object. Per the Proxy set trap specification, when receiver !== proxy (e.g., when a child object inherits from the proxy via Object.create), the property assignment should create an own property on the receiver, not on the proxy target. The current implementation always calls otherReflectSet(object, key, value) against the host target, causing all inherited property writes to leak through to the host object. This bug provides an alternative attack vector for writing dangerous cross-realm Symbol keys (e.g., nodejs.util.promisify.custom) to host objects, bypassing any future per-trap isDangerousCrossRealmSymbol guard on the direct set path. This issue has been patched in version 3.11.4.
Weakness: CWE-693
Which versions are affected by CVE-2026-47209?
2 open source packages ship an affected version, including vm2.
| Package | Affected | Fixed in |
|---|---|---|
vm2 npm | All versions | 3.11.4 |
vm2 npm | All versions | 3.11.4 |
How do I fix CVE-2026-47209?
Upgrade vm2 to 3.11.4 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-47209 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47209 exists.
Sources
Also known as ECHO-7db5-a96e-2943, GHSA-c4cf-2hgv-2qv6, MINI-vpj7-8pmf-r3jc, ROOT-APP-NPM-CVE-2026-47209.