Vulnerability in vm2 (CVE-2026-44000)
Summary
Vulnerability in vm2 (CVE-2026-44000). Risk of unauthorized operations or information disclosure. Exploitable via WeakMap. Mitigation: upgrade to 3.11.0 or later.
Original description
The description as published by the source.
Summary
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 - 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.
Details
In setup-sandbox.js, vm2 wraps Promise.prototype.then:
globalPromise.prototype.then = function then(onFulfilled, onRejected) {
resetPromiseSpecies(this);
if (typeof onFulfilled === 'function') {
const origOnFulfilled = onFulfilled;
onFulfilled = function onFulfilled(value) {
value = ensureThis(value);
return apply(origOnFulfilled, this, [value]);
};
}
return apply(globalPromiseThen, this, [onFulfilled, onRejected]);
};
The wrapper calls ensureThis(value) before invoking the sandbox callback.
However, ensureThis is implemented in bridge.js as thisEnsureThis():
function thisEnsureThis(other)…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-44000 has been found in vm2.
Attackers can target a specific entry point like WeakMap over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: upgrade vm2 to 3.11.0 or later.
If unsure, ask your IT team or search "vm2 CVE-2026-44000" on the vendor's site.
CVE-2026-44000 (vm2) — CWE-668 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: WeakMap / Promise.prototype.then
Patched: 3.11.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-668) exists in vm2. Attackers reach the vulnerable code path via WeakMap without authentication.
Check the vendor advisory for the affected versions of vm2. Attack surface: WeakMap / Promise.prototype.then.
Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.
Update to 3.11.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'vm2' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'vm2' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
vm2を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade vm2 to 3.11.0ステージング環境で 3.11.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com