Vulnerability in Patriksimek Vm2
CVE-2026-44000
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Patriksimek Vm2 — versions < 3.11.0
- Vm2 Project
Weakness classification (CWE)
References
- github.com/patriksimek/vm2/security/advisories/GHSA-mpf8-4hx2-7cjg (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-44000?
- CVE-2026-44000 is a medium-severity vulnerability in Patriksimek Vm2, classified under Protection Mechanism Failure. CVSS score: 6.5/10. Published 2026-05-13.
- How severe is CVE-2026-44000?
- Medium severity. CVSS v3 base score is 6.5 out of 10.