What is CVE-2026-93606?

CVE-2026-93606 is a critical-severity vulnerability in Patriksimek Vm2, classified under Protection Mechanism Failure. CVSS score: 10.0/10. Published 2026-09-18.

How severe is CVE-2026-93606?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Vulnerability in Patriksimek Vm2

CVE-2026-93606

vm2 (npm) versions 3.12.0 and earlier contain a sandbox escape in `VM` and `NodeVM`. When an embedder exposes a host API that returns a host-realm Promise, the bridge's rejection sanitizer (hostPromiseSanitizeReject / makeSanitizedPromiseCallback / normalizeHostPromiseCallbacks in lib/bridge.js) only wraps `then`/`catch` rejection slots that hold a function, and the sandbox-side `Symbol.species`/`.then` neutralization is installed only on the sandbox intrinsic `Promise.prototype`, so it never applies to a host Promise. Code running inside the sandbox can overwrite `p.constructor[Symbol.species]` on the host Promise and then call `p.then()` with no `onRejected` handler; V8 substitutes its internal Thrower, which re-throws the raw host rejection value into a resolve/reject closure captured by the attacker. This delivers an unsanitized, fully functional bridge proxy of the host object to sandboxed code, bypassing handleException and hostPromiseSanitizeReject. If the rejection value is host-pivotable (for example a host `process` object), this results in arbitrary code execution on the host. Fixed in 3.12.1.

Published 2026-09-18 · last modified 2026-09-18.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (53.6th percentile), scored 2026-11-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Patriksimek Vm2

Weakness classification (CWE)

CWE-693 — Protection Mechanism Failure

References

github.com/patriksimek/vm2/security/advisories/GHSA-6454-5x88-m6jw (vendor-advisory)
www.vulncheck.com/advisories/vm2-before-3.12.1-sandbox-escape-via-promise-symbo… (third-party-advisory)

Frequently asked questions

What is CVE-2026-93606?: CVE-2026-93606 is a critical-severity vulnerability in Patriksimek Vm2, classified under Protection Mechanism Failure. CVSS score: 10.0/10. Published 2026-09-18.
How severe is CVE-2026-93606?: Critical severity. CVSS v3 base score is 10.0 out of 10.