CVE 6.5 MEDIUM

vm2: sandbox boundary bypass via host Promise resolution preserving host object identity_CVE-2026-44000

6.5 / 10
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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.

Basic Information

ID CVE-2026-44000
Source GitHub_M
Published May 13, 2026 at 17:23

Affected Product

Vendor patriksimek
Product vm2
Version < 3.11.0
Affected Versions patriksimek vm2 < 3.11.0

CWE Classification

References

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