vm2's bufferAllocLimit cap bypassed by Buffer.concat and Buffer.from arrayLike

Exploitation

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

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-47683: 0.54% estimated exploitation activity in the next 30 days; percentile 45.34 (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 vm2 bufferAllocLimit cap bypassed by Buffer.concat and Buffer.from arrayLike The bufferAllocLimit option introduced in 3.11.0 (GHSA-6785-pvv7-mvg7) caps host-side Buffer allocations driven by sandbox code, the way embedders opt into timeout. The cap wraps Buffer.alloc, Buffer.allocUnsafe, Buffer.allocUnsafeSlow, and the deprecated Buffer(N) / new Buffer(N) forms. Two other API paths reach the same host C++ allocator with an attacker-controlled size and are not capped: Buffer.concat(list, totalLength) and Buffer.from(arrayLike) with a fake length. Sandbox code can use either to allocate an arbitrary number of host external bytes in a single call, defeating the explicit DoS mitigation the embedder configured. Details lib/setup-sandbox.js installs checkBufferAllocLimit at every wrapped entry to host Buffer allocation: - alloc() at lib/setup-sandbox.js:474 and the connect(alloc, host.Buffer.alloc) at line 480. - allocUnsafe() at line 488 and connect(allocUnsafe,…

Published by the source

17 Aug 2026, 17:32 UTC

Last modified by the source

17 Aug 2026, 17:32 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gmc2-2x9w-cgh9

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# Patch Next advisory brief: CVE-2026-47683

Advisory: vm2's bufferAllocLimit cap bypassed by Buffer.concat and Buffer.from arrayLike
IDs: CVE-2026-47683, GHSA-gmc2-2x9w-cgh9
Record: https://patchnext.com/advisories/cve-2026-47683 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vm2 3.11.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm vm2: affected <= 3.11.5; fixed in 3.11.6

## 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://github.com/advisories/GHSA-gmc2-2x9w-cgh9 (GitHub-reviewed advisory GHSA-gmc2-2x9w-cgh9 lists affected ranges: npm vm2 >=0 <=3.11.5)

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