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Description

NanaZip is the 7-Zip derivative intended for the modern Windows experience. Prior to 6.5.1749.0, NanaZip's UFS and FFS image handler in NanaZip.Codecs.Archive.Ufs.cpp validates the superblock block size only against the MINBSIZE lower bound and does not validate the fs_fsize fragment size, allowing attacker-controlled 32-bit fields to flow into indirect-block, directory, and extraction buffer allocations. A tiny crafted UFS image can force multi-gigabyte allocations during open or extraction, causing memory exhaustion or process termination. This issue is fixed in version 6.5.1749.0.

PUBLISHED Reserved 2026-06-17 | Published 2026-07-10 | Updated 2026-07-10 | Assigner GitHub_M




LOW: 2.4CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Problem types

CWE-400: Uncontrolled Resource Consumption

CWE-789: Memory Allocation with Excessive Size Value

Product status

< 6.5.1749.0
affected

References

github.com/...anaZip/security/advisories/GHSA-m34h-jf84-m74h

github.com/...ommit/6415b6bff70bc9c486b49cbbc1982724c67f8338

github.com/M2Team/NanaZip/releases/tag/6.5.1749.0

cve.org (CVE-2026-55781)

nvd.nist.gov (CVE-2026-55781)

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