Quick answers
- Is This vulnerability exploited in the wild?
- No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
- How severe is This vulnerability?
- High severity, with a CVSS score of 7.5, published 27 September 2026.
- Which products and versions are affected?
- vm2 (npm) < 3.12.2; Vm2 before 3.12.2.
- Is there a fix for This vulnerability?
- Yes: fixed in 3.12.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked over the network, in a software library.
- Am I affected?
- Check whether you run vm2 (npm) or Vm2 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 3.12.2
Technical details
The vulnerability stems from vm2's failure to enforce its buffer backing-store ownership invariant (byteOffset === 0 and buffer.byteLength === length) on Buffers returned from host builtin modules. When zlib.deflateSync returns a small buffer from Node's shared pool, guest code can construct a full-width view of the pool's entire ArrayBuffer via Buffer.from(result.buffer, 0, result.buffer.byteLength), bypassing isolation. The attack requires explicit allowlisting of zlib in NodeVM's require configuration.
Affected products
- vm2 before 3.12.2
Timeline
- 2026-09-08: disclosed
- 2026-09-27: patched