CVE-2026-55780: NanaZip is the 7-Zip derivative intended for the modern Windows experience

Routine

LOW 2.4

CVE-2026-55780 is a low-severity flaw (CVSS 2.4) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 esc

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	2.4 (Low)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	Passive
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-248, CWE-400
Published	2026-07-10
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc.

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-07-10 17:16 UTCPublished CVE record published
2026-10-25 15:10 UTCUpdated Record last modified

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: NanaZip 6.5 - DoS

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-55780?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-55780 being exploited?

CVE-2026-55780 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-55780 affect?

CVE-2026-55780 affects affected software. Severity is low (CVSS 2.4). 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

How urgent is CVE-2026-55780?

Priority 23/100. Public exploit reference

Software pages

Windows vulnerabilities · 7-Zip vulnerabilities

References

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