Quick answers
- Is CVE-2026-55783 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-55783 being exploited in the wild.
- How severe is CVE-2026-55783?
- Informational severity, with a CVSS score of 2.4, published 10 July 2026.
- Which products and versions are affected?
- M2Team NanaZip < 6.5.1749.0.
- Is there a fix for CVE-2026-55783?
- A patch was published on 2026-06-16: Fixed in version 6.5.1749.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-55783 attacked?
- It is attacked with local access, in a network appliance.
- Am I affected by CVE-2026-55783?
- 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
A NULL pointer dereference exists in NanaZip's seven in-house IInArchive handlers within NanaZip.Codecs. When the archive engine signals a 'test' or 'extract all' operation, it passes a NULL Indices array and a NumItems value of 0xFFFFFFFF. The vulnerable handlers (WebAssembly, ElectronAsar, Zealfs, Romfs, Ufs, Littlefs, and DotNetSingleFile) fail to check for the NULL array before dereferencing it during the GetStream call. An attacker can trigger this by providing a malicious archive file that causes a process crash when the victim performs standard extraction or testing actions. The issue is resolved in version 6.5.1749.0 by correctly using the pre-computed ActualFileIndex.
Affected products
- M2Team NanaZip < 6.5.1749.0
Timeline
- 2026-06-16: patched: Fixed in version 6.5.1749.0
- 2026-06-16: advisory: GitHub Security Advisory GHSA-q67r-9cfh-xc29 published
- 2026-07-10: disclosed: CVE-2026-55783 published to NVD