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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/patriksimek/vm2/commit/4f2508abeb252aa86eb6761c78b3b000248fb…
disclosure@vulncheck.com
https://github.com/patriksimek/vm2/commit/5214b02ef13b82497fcb917b45320dfd014ff…
disclosure@vulncheck.com
https://github.com/patriksimek/vm2/security/advisories/GHSA-489w-w794-jq94
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/vm2-before-3.12.2-memory-disclosure-via-zl…
disclosure@vulncheck.com