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.

A heap out-of-bounds read vulnerability exists in NanaZip versions 1.0.88.0 through 6.0.1698.0 (stable) and 6.5.1742.0 (preview). The flaw resides in the Lz4Decode function within SquashfsHandler.cpp, where negative error values returned by LZ4_decompress_safe are not properly handled. The negative integer is incorrectly converted to an unsigned SizeT, causing ReadBlock to trust an attacker-inflated cached unpack block size. During SquashFS fragment extraction, an attacker-controlled inode offset can trigger a memcpy that reads beyond the allocated heap buffer, potentially leaking adjacent heap memory contents into the extracted file or crashing the process. This represents a significant information disclosure and denial-of-service risk when processing maliciously crafted SquashFS archives. The vulnerability is fixed in stable version 6.0.1698.0 and preview version 6.5.1742.0. Users are strongly advised to update to the patched releases immediately.