Medium

CVE-2026-42443 — NanaZip: Integer divide-by-zero in NanaZip UFS inode offset calculation

NanaZip is an open source file archive. From 5.0.1252.0 to before 6.0.1698.0, an integer divide-by-zero exists in the UFS/UFS2 filesystem image parser in NanaZip. The vulnerability is triggered when opening a crafted UFS image where the superblock field fs_ipg (inodes per cylinder group) is set to zero. The parser uses this attacker-controlled value as a divisor without validation, causing an immediate hardware trap and process crash. This vulnerability is fixed in 6.0.1698.0.

Published May 12, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.1% (30-day exploitation probability)+1
Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.15%

ahead of 4% of scored CVEs · Oct 14, 2026

Affects

M2team

Nanazip

CVSS base

5.5

Medium · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented mitigation — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (M2team Nanazip).
Apply the documented mitigations until a definitive fix is available.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
M2team	Nanazip	≥ 5.0.1252.0 and < 6.0.1698.0	Vulnerable	NIST National Vulnerability Database
M2team	Nanazip	version >= 5.0.1250.0, < 6.0.1698.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

None

User interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.5	CVSS 3.1	Medium	1.8	3.6	nvd@nist.gov via NIST National Vulnerability Database
3.3	CVSS 3.1	Low	1.8	1.4	security-advisories@github.com via NIST National Vulnerability Database
3.3	CVSS 3.1	Low	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 5.5 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-369

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.15%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.

endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · m2team/nanazip
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 5.5
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 12, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

github.com/M2Team/NanaZip/security/advisories/GHSA-3x2h-gqqw-g3gm
Mitigation, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

M2team
every CVE for this vendor

CWE-369
other pages naming this weakness

Related CVEs (same products)

Low CVE-2026-55783 NanaZip: NULL pointer dereference in Extract() of all seven NanaZip custom archive handlers when extracting/testing the whole archive Jul 10, 2026
Low CVE-2026-55782 NanaZip: Unbounded memory allocation (DoS) in NanaZip WebAssembly parser via attacker-controlled section/name length fields Jul 10, 2026
Low CVE-2026-55781 NanaZip: Unbounded memory allocation (DoS) in NanaZip UFS parser via unvalidated fs_bsize/fs_fsize superblock fields Jul 10, 2026
Low CVE-2026-55780 NanaZip: Uncaught exception / unbounded allocation in NanaZip .NET single-file Extract() via unvalidated entry Size Jul 10, 2026
Medium CVE-2026-47223 NanaZip: Heap out-of-bounds read in NanaZip AVB hashtree descriptor parser via 32-bit unsigned integer overflow Jun 12, 2026
Medium CVE-2026-47224 NanaZip: Heap buffer-overflow read in NanaZip LVM metadata CRC check Jun 12, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-42443 is "NanaZip: Integer divide-by-zero in NanaZip UFS inode offset calculation", rated Medium. It affects Nanazip (M2team); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.15% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.