Vulnerability · Published May 12, 2026 · Assigned by GitHub_M

CVE-2026-42446NanaZip: Stack out-of-bounds read in NanaZip ZealFS bitmap parser

Medium 4.4

In plain English

A medium-severity out-of-bounds read in NanaZip from M2Team. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 3.1)4.4Medium

Exploit odds (30 days)0.1%top 98.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

NanaZip is an open source file archive. From 5.0.1252.0 to before 6.0.1698.0, a stack-based out-of-bounds read exists in the ZealFS filesystem image parser in NanaZip. The vulnerability is triggered when opening a crafted ZealFS v1 filesystem image. An attacker-controlled BitmapSize field in the file header drives an unbounded loop that reads past the end of a stack-allocated ZEALFS_V1_HEADER structure. This vulnerability is fixed in 6.0.1698.0.

Affected products (as reported)

Vendor	Product	Versions
M2Team	NanaZip	>= 5.0.1250.0, < 6.0.1698.0

Weakness: CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L

References

https://github.com/M2Team/NanaZip/security/advisories/GHSA-4c79-hfr4-mqv9 x_refsource_CONFIRM