CVE-2026-55781

UNKNOWN 0.0

NanaZip: Unbounded memory allocation (DoS) in NanaZip UFS parser via unvalidated fs_bsize/fs_fsize superblock fields

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-400 CWE-789
Vendor	m2team
Product	nanazip
Published	Jul 10, 2026
Last Updated	Jul 10, 2026

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Affected Versions

M2Team / NanaZip

< 6.5.1749.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/M2Team/NanaZip/security/advisories/GHSA-m34h-jf84-m74h github.com: https://github.com/M2Team/NanaZip/commit/6415b6bff70bc9c486b49cbbc1982724c67f8338 github.com: https://github.com/M2Team/NanaZip/releases/tag/6.5.1749.0