CVE-2026-100723
vm2 before 3.12.2 Memory Disclosure via zlib Buffer Pool
MEDIUM 6.9EPSS 0.3%
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
- patriksimek · vm2
- CVSS v4.0 VULNCHECK
- 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS v4.0 GitHub
- 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N - CVSS v3.1 VULNCHECK
- 7.5 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N - CVSS v3.1 GitHub
- 10.0 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N - EPSS
- 0.32% chance of exploitation in the next 30 days, 23rd percentile
- Published
- 2026-09-27
- Updated
- 2026-10-01