Vulnerability · Published Sep 27, 2026 · Assigned by VulnCheck

CVE-2026-100723vm2 before 3.12.2 Memory Disclosure via zlib Buffer Pool

High 7.5

In plain English

A high-severity information exposure in vm2 from patriksimek. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 66.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

vm2 before 3.12.2 does not apply its Buffer backing-store ownership invariant (byteOffset === 0 and buffer.byteLength === length) to Buffers returned from host builtin modules. When an application explicitly exposes Node's zlib module through NodeVM's builtin allowlist (require: { builtin: ['zlib'] }), zlib.deflateSync can return a Buffer backed by Node's shared small-buffer pool whose .buffer is the entire pool. Untrusted guest code can construct a full-width view of that ArrayBuffer (Buffer.from(result.buffer, 0, result.buffer.byteLength)) to read and modify bytes belonging to unrelated host buffers, disclosing and corrupting host-realm memory across the sandbox boundary.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	vm2	3.12.2	GHSA-489w-w794-jq94

Affected products (as reported)

Vendor	Product	Versions
patriksimek	vm2	0 – before 3.12.2

Weakness: CWE-200 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N

References

GitHub Security Advisory (GHSA-489w-w794-jq94) vendor-advisory
Patch Commit patch
Patch Commit patch
VulnCheck Advisory: vm2 before 3.12.2 Memory Disclosure via zlib Buffer Pool third-party-advisory