NanaZip, an open source archive manager, contains a one‑byte heap out‑of‑bounds null write in its UFS/UFS2 filesystem image parser. The flaw causes a memory corruption when parsing a maliciously crafted UFS archive. This vulnerability is a classic out‑of‑bounds write (CWE‑787) and can potentially lead to process crashes or, if a more advanced exploit chain is employed, to arbitrary code execution.

The affected product is M2Team NanaZip version 5.0.1252.0 up to, but not including, 6.0.1698.0. Users running any of these versions in an environment that can open UFS images are impacted. The update to 6.0.1698.0 addresses the issue.

The CVSS score of 4.4 indicates a medium severity and the EPSS score is not available, so the exact exploitation probability is unknown. The vulnerability is not listed in the CISA KEV catalog. Based on the description, it is inferred that the attack vector involves supplying or opening a crafted UFS image. If an application allows untrusted users to upload or submit archive files, the vulnerability could be triggered remotely via a web service or other input channel. If the archive is processed locally, the threat is limited to the local user or any process that uses NanaZip to extract the image.