CVE-2026-100723 vm2 before 3.12.2 Memory Disclosure via zlib Buffer Pool
Untrusted code in vm2 can read and modify host memory via zlib buffers if the zlib module is explicitly allowed in the sandbox configuration.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-100723?
CVE-2026-100723 is a medium-severity vulnerability in patriksimek vm2, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-200
Which versions are affected by CVE-2026-100723?
2 open source packages ship an affected version, including vm2.
| Package | Affected | Fixed in |
|---|---|---|
vm2 npm | All versions | 3.12.2 |
vm2 npm | All versions | 3.12.2 |
How do I fix CVE-2026-100723?
Upgrade vm2 to 3.12.2 or later.
Is CVE-2026-100723 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100723 exists.
Sources
Also known as ECHO-bd4e-a735-8188, GHSA-489w-w794-jq94, MINI-3m46-pr38-c95q.