CVE-2026-54616: m2team Nanazip

High severity, CVSS 7.1. EPSS: 0.4% chance of exploitation in the next 30 days.

NanaZip is the 7-Zip derivative intended for the modern Windows experience. From version 1.0.88.0 until stable version 6.0.1698.0 and preview version 6.5.1742.0, the Lz4Decode function in NanaZip.Core/SevenZip/CPP/7zip/Archive/SquashfsHandler.cpp rejects only a zero return from LZ4_decompress_safe even though malformed input produces a negative error value. The negative int is converted to the unsigned SizeT destLen and then truncated into outBufWasWrittenSize, causing ReadBlock to trust an attacker-inflated _cachedUnpackBlockSize. During fragment extraction, an attacker-controlled inode Offset can make memcpy read beyond the _cachedBlock heap allocation and place adjacent heap contents in the extracted file, or crash the process. This issue is fixed in stable version 6.0.1698.0 and preview version 6.5.1742.0.

Affected products

• m2team Nanazip: from 1.0.88.0, before 6.0.1698.0 (fixed in 6.0.1698.0); from 6.5.1638.0, before 6.5.1742.0 (fixed in 6.5.1742.0)

Published 2026-08-20. Last modified 2026-09-18.