CVE-2026-42446 NanaZip: Stack out-of-bounds read in NanaZip ZealFS bitmap parser

Medium 4.4 Published 12 May 2026 Updated 13 May 2026

An attacker can cause a denial of service in NanaZip by tricking a user into opening a crafted ZealFS filesystem image that triggers a stack out-of-bounds read.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-42446?

CVE-2026-42446 is a medium-severity memory corruption vulnerability in M2Team NanaZip, published on 12 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

NanaZip is an open source file archive. From 5.0.1252.0 to before 6.0.1698.0, a stack-based out-of-bounds read exists in the ZealFS filesystem image parser in NanaZip. The vulnerability is triggered when opening a crafted ZealFS v1 filesystem image. An attacker-controlled BitmapSize field in the file header drives an unbounded loop that reads past the end of a stack-allocated ZEALFS_V1_HEADER structure. This vulnerability is fixed in 6.0.1698.0.

Weakness: CWE-125

Which versions are affected by CVE-2026-42446?

It affects 1 product.

Products include M2team Nanazip.

How do I fix CVE-2026-42446?

No fix has been published for CVE-2026-42446 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-42446 being exploited?

There is no known exploitation of CVE-2026-42446 in the wild and no public exploit code.

Sources

Also known as GHSA-4c79-hfr4-mqv9.