CVE-2026-55781: m2team Nanazip

Low severity, CVSS 2.4. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• m2team Nanazip: before 6.5.1749.0 (fixed in 6.5.1749.0)

Published 2026-07-10. Last modified 2026-07-10.