CVE-2026-55780 NanaZip: Uncaught exception / unbounded allocation in NanaZip .NET single-file Extract() via unvalidated entry Size
A crafted .NET single-file bundle can cause an unhandled exception and crash NanaZip due to unvalidated entry size fields.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-55780?
CVE-2026-55780 is a low-severity denial of service vulnerability in M2Team NanaZip, published on 10 Jul 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 the 7-Zip derivative intended for the modern Windows experience. Prior to 6.5.1749.0, NanaZip's .NET single-file bundle handler in NanaZip.Codecs.Archive.DotNetSingleFile.cpp sizes its extraction buffer from the bundle entry Size field, which is only checked for sign and is not validated against the real file size. A crafted bundle can cause an attacker-chosen allocation inside Extract, where std::bad_alloc or std::length_error can escape across the COM STDMETHODCALLTYPE boundary and crash the process. This issue is fixed in version 6.5.1749.0.
Which versions are affected by CVE-2026-55780?
How do I fix CVE-2026-55780?
No fix has been published for CVE-2026-55780 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-55780 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55780 exists.
Public exploit code: 1 Exploit-DB entry.
Sources
Also known as GHSA-ppm9-5267-rq72.