CVE-2026-100723: Patriksimek VM2

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

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 products

• Patriksimek VM2: before 3.12.2 (fixed in 3.12.2)

Published 2026-09-27. Last modified 2026-10-01.