Vulnerability · Published May 13, 2026 · Assigned by GitHub_M
CVE-2026-44000vm2: sandbox boundary bypass via host Promise resolution preserving host object identity
Medium 6.5
In plain English
A medium-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 0.2% (higher than 10% 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 3.11.0, a sandbox boundary violation in vm2 allows host object identity to cross into the sandbox through host Promise resolution. When a host-side Promise that resolves to a host object is exposed to the sandbox, the value delivered to the sandbox .then() callback preserves host identity. This allows the sandbox to interact with the host object directly, including performing identity checks using host-side WeakMap and mutating host object state from inside the sandbox. This behavior occurs because the Promise fulfillment wrapper uses ensureThis() instead of the stronger cross-realm conversion path (from() / proxy wrapping). If no prototype mapping is found, ensureThis() returns the original object. As a result, objects resolved by host Promises can cross the sandbox boundary without proper isolation. This vulnerability is fixed in 3.11.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | vm2 | 3.11.0 | GHSA-mpf8-4hx2-7cjg |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| patriksimek | vm2 | < 3.11.0 |
Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
References
- https://github.com/patriksimek/vm2/security/advisories/GHSA-mpf8-4hx2-7cjg x_refsource_CONFIRM