patriksimek vm2 up to 3.12.1 Buffer zlib.deflateSync buffer overflow

Summaryinfo

A vulnerability was found in patriksimek vm2 up to 3.12.1 and classified as critical. This affects the function zlib.deflateSync of the component Buffer. Executing a manipulation can lead to buffer overflow. The identification of this vulnerability is CVE-2026-100723. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in patriksimek vm2 up to 3.12.1 and classified as critical. This vulnerability affects the function zlib.deflateSync of the component Buffer. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-100723 since 09/26/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

Upgrading to version 3.12.2 eliminates this vulnerability.

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Productinfo

Vendor

• patriksimek

Name

• vm2

Version

• 3.12.0
• 3.12.1

Website

• Product: https://github.com/patriksimek/vm2/

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