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CVE-2026-44004 high CVSS 7.5

Vulnerability in vm2 (CVE-2026-44004)

Summary

Vulnerability in vm2 (CVE-2026-44004). Risk of unauthorized operations or information disclosure. Exploitable via Buffer.alloc. Mitigation: upgrade to 3.11.0 or later.

Original description

The description as published by the source.

Summary

Sandboxed code can call Buffer.alloc() with an arbitrary size to allocate memory directly on the host heap. Because Buffer.alloc is a synchronous C++ native call, vm2's timeout option cannot interrupt it. A single request can exhaust host memory and crash the process with a FATAL ERROR: Reached heap limit.

Details

In lib/vm.js:58, Buffer is exposed to the sandbox through the HOST object. The bridge proxy (lib/bridge.js) passes Buffer.alloc() calls to the host without any size validation.

Key technical distinction from regular JavaScript memory exhaustion (e.g., while(true) a.push(...)):

  • JavaScript loops: V8 can interrupt via timeout — vm2's timeout option works
  • Buffer.alloc(N): Executes as a single synchronous C++ call — V8 timeout has no opportunity to interrupt

This means:

  1. timeout: 5000 does NOT protect against this attack
  2. A single call allocates the entire requested size at once
  3. In memory-constrained environments (Docker, Lambda, Kubernetes pods), this causes immediate OOM crash

Tested amplification factor: ~100 bytes HTTP request — 1,000,000:1 or greater (100 bytes request to 100MB+ host heap allocation).

PoC

Library-level PoC (Node.js script — primary):

const { VM } = require("vm2");
const vm = new VM({ timeout: 5000 });

// Buffer.alloc bypasses timeout — allocates 100MB on host heap
const result = vm.run(`Buffer.alloc(1024*1024*100).length`);
console.log(result); // 104857600 — t…

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-2026-44004 has been found in vm2.
Attackers can target a specific entry point like Buffer.alloc over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade vm2 to 3.11.0 or later.
If unsure, ask your IT team or search "vm2 CVE-2026-44004" on the vendor's site.

CVE-2026-44004 (vm2) — CWE-770 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Buffer.alloc / timeout / Buffer / HOST
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.

❓ What is the problem

A vulnerability (CWE-770) exists in vm2. Attackers reach the vulnerable code path via Buffer.alloc without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of vm2. Attack surface: Buffer.alloc / timeout / Buffer / HOST.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.11.0.

🛡️ 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 3.11.0

    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。

  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":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.11.0"}]}]

References

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