# CVE-2026-42443: M2Team NanaZip integer divide-by-zero in UFS filesystem parser

Source: https://junglewise.ai/threats/cve-2026-42443-m2team-nanazip-integer-divide-by-zero-in-ufs-filesystem-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-12. Updated: 2026-05-18  
License: CC BY 4.0 with a link back

CVE-2026-42443 · Severity: low · CVSS 3.3 · Published 2026-05-12

NanaZip is an open-source file archiver used to compress and decompress various file formats. A vulnerability in how it handles specific filesystem images (UFS/UFS2) allows an attacker to crash the application by providing a specially crafted file. While this does not lead to data theft or unauthorized access, it results in a denial-of-service where the software stops responding or closes unexpectedly when the malicious file is opened.

Technologies: [M2Team NanaZip](https://junglewise.ai/threats/technologies/nanazip). Vendors: [M2Team](https://junglewise.ai/threats/vendors/m2team).

## Quick answers

**Is CVE-2026-42443 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42443 being exploited in the wild.

**How severe is CVE-2026-42443?** Low severity, with a CVSS score of 3.3, published 12 May 2026.

**Which products and versions are affected?** M2Team NanaZip 5.0.1252.0 to before 6.0.1698.0.

**Is there a fix for CVE-2026-42443?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-42443 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-42443?** Check whether you run M2Team NanaZip at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An integer divide-by-zero vulnerability exists in the UFS/UFS2 filesystem image parser within NanaZip. The flaw is located in the GetInodeOffset function in NanaZip.Codecs.Archive.Ufs.cpp, where the superblock field 'fs_ipg' (inodes per cylinder group) is read from the disk and used as a divisor without validation. If an attacker provides a crafted UFS image with 'fs_ipg' set to zero, the application triggers a hardware divide-by-zero exception (x86 #DE), leading to an immediate process crash. This occurs during the archive opening phase (IInArchive::Open) before user interaction beyond selecting the file. The issue is fixed in version 6.0.1698.0.

## Affected products

- M2Team NanaZip 5.0.1252.0 to before 6.0.1698.0

## Timeline

- 2026-04-27: advisory: GitHub Security Advisory published by M2Team
- 2026-05-12: disclosed: CVE-2026-42443 published to NVD

## References

- [https://github.com/M2Team/NanaZip/security/advisories/GHSA-3x2h-gqqw-g3gm](https://github.com/M2Team/NanaZip/security/advisories/GHSA-3x2h-gqqw-g3gm)

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- [M2Team NanaZip NULL pointer dereference in NanaZip.Codecs archive handlers](https://junglewise.ai/threats/cve-2026-55783-m2team-nanazip-null-pointer-dereference-in-nanazip-codecs-archive)
- [M2Team NanaZip uncontrolled memory allocation in WebAssembly handler](https://junglewise.ai/threats/cve-2026-55782-m2team-nanazip-uncontrolled-memory-allocation-in-webassembly)
- [M2Team NanaZip memory exhaustion in UFS and FFS image handler](https://junglewise.ai/threats/cve-2026-55781-m2team-nanazip-memory-exhaustion-in-ufs-and-ffs-image-handler)
- [M2Team NanaZip uncaught exception in .NET single-file handler](https://junglewise.ai/threats/cve-2026-55780-m2team-nanazip-uncaught-exception-in-net-single-file-handler)