Executive brief
NanaZip is an open-source file archiver used to compress and extract various file formats. A security flaw in how it handles UFS filesystem images allows a specially crafted file to corrupt the application's memory when opened. This could lead to the program crashing or potentially allow more sophisticated attacks, though it requires a user to manually open the malicious file.
Technical details
A one-byte heap out-of-bounds null write exists in the UFS/UFS2 filesystem image parser within NanaZip's GetAllPaths function. The vulnerability is caused by a failure to verify that the name length (d_namlen) plus a null terminator fits within the directory record length (d_reclen) or the allocated buffer. An attacker can trigger this by providing a crafted UFS image where a directory entry is placed at the end of a block with a maximum name length value. This allows a null byte to be written up to 254 bytes past the heap allocation boundary. While modern Windows mitigations (CFG, CET) make exploitation difficult, the flaw can cause a denial of service or be used as a primitive for further heap corruption. The issue is fixed in version 6.0.1698.0.
Affected products
- M2Team NanaZip 5.0.1252.0 to 6.0.1698.0
Timeline
- 2026-04-27: advisory: GitHub Security Advisory published by MouriNaruto
- 2026-05-12: disclosed: CVE-2026-44215 published