vm2 Sandbox Access to Host Buffer.alloc Allows timeout Bypass Resulting in Memory Exhaustion

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-44004: 0.42% estimated exploitation activity in the next 30 days; percentile 36.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

7 May 2026, 04:26 UTC

Last modified by the source

14 May 2026, 20:48 UTC

Source last checked

26 Oct 2026, 12:52 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-6785-pvv7-mvg7

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-6785-pvv7-mvg7

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# Patch Next advisory brief: CVE-2026-44004

Advisory: vm2 Sandbox Access to Host Buffer.alloc Allows timeout Bypass Resulting in Memory Exhaustion
IDs: CVE-2026-44004, GHSA-6785-pvv7-mvg7
Record: https://patchnext.com/advisories/cve-2026-44004 (revision 2, source checked 26 Oct 2026, 12:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vm2 3.11.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm vm2: affected <= 3.10.5; fixed in 3.11.0

## Suggested inspection (read-only)
- `npm ls vm2 --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vm2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-6785-pvv7-mvg7 (OSV record GHSA-6785-pvv7-mvg7 lists affected ranges: npm vm2 >=0 <3.11.0 (fixed))
- Verified: https://github.com/advisories/GHSA-6785-pvv7-mvg7 (GitHub-reviewed advisory GHSA-6785-pvv7-mvg7 lists affected ranges: npm vm2 >=0 <=3.10.5)

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