CVE-2026-47209CWE-693

vm2: Bridge Proxy set trap ignores receiver parameter, enabling host object property injection via prototype chain

High · published June 12, 2026

CVSS v3.1
8.6
EPSS
1%
Percentile
42.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.6 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00506 · 42.4th percentile
Weakness
CWE-693 · Protection Mechanism Failure
Published
2026-06-12T14:14Z
EPSS history
Timeline
  • 12 JUN 14:14Z
    vm2: Bridge Proxy set trap ignores receiver parameter, enabling host object property injection via prototype chain
    cvelistv5