Bug 2542016 (CVE-2026-100723)

Summary: CVE-2026-100723 vm2: vm2: Information disclosure via zlib shared buffer pool
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abarbaro, alizardo, dschmidt, ikhan, jchui, jhe, jlanda, kshier, ktsao, nboldt, oaljalju, psrna, rbobbitt, simaishi, stcannon, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in vm2. When an application permits the sandbox to access built-in Node.js modules such as the zlib compression library, returned data buffers fail to maintain memory isolation from the host system. An attacker executing untrusted code within the sandbox can inspect and alter the underlying shared memory pool, resulting in sensitive information disclosure and memory corruption across the sandbox boundary.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-09-27 01:52:54 UTC
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.