Vulnerability · Published Jun 12, 2026 · Assigned by GitHub_M
CVE-2026-47209vm2: Bridge Proxy set trap ignores receiver parameter, enabling host object property injection via prototype chain
High 8.6
In plain English
A high-severity security flaw in vm2 from patriksimek. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | vm2 | 3.11.4 | GHSA-c4cf-2hgv-2qv6 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| patriksimek | vm2 | < 3.11.4 |
Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
References
- https://github.com/patriksimek/vm2/security/advisories/GHSA-c4cf-2hgv-2qv6 x_refsource_CONFIRM
- https://github.com/patriksimek/vm2/commit/26d0318b5e6555be4b187ba05d6cf378ccecfe22 x_refsource_MISC
- https://github.com/patriksimek/vm2/releases/tag/v3.11.4 x_refsource_MISC