Vulnerability 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.
Related Weaknesses (CWE)
References
- https://github.com/M2Team/NanaZip/commit/6415b6bff70bc9c486b49cbbc1982724c67f833
- https://github.com/M2Team/NanaZip/releases/tag/6.5.1749.0
- https://github.com/M2Team/NanaZip/security/advisories/GHSA-m34h-jf84-m74h
FAQ
What is CVE-2026-55781?
CVE-2026-55781 is a documented vulnerability. 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 si...
How severe is CVE-2026-55781?
CVSS scoring is not yet available for CVE-2026-55781. Check NVD for updates.
Is there a patch for CVE-2026-55781?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.