Bug 2564058 (CVE-2026-119602)

Summary: CVE-2026-119602 libmspack: libmspack: Information disclosure via unchecked back-references in MS-ZIP decompressor
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libmspack. The MS-ZIP decompressor fails to properly validate back-reference distances when decompressing cabinet (CAB) archive files. By providing a specially crafted archive whose initial block starts with a back-reference, an attacker can cause the extraction routine to copy uninitialized heap memory into the extracted file. This flaw leads to information disclosure, potentially exposing sensitive data stored in memory.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-30 14:19:47 UTC
libmspack through 0.11alpha contains an uninitialized memory disclosure vulnerability in the MS-ZIP decompressor that allows attackers to leak heap data via unchecked back-reference distances. Attackers can supply a crafted MS-ZIP CAB file whose first block begins with a back-reference, causing cabd->extract() to write up to 32 KiB of stale heap memory into extracted output.