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TI-2026-40270 Aliases CVE-2026-55781

NanaZip: Unbounded memory allocation (DoS) in NanaZip UFS parser via unvalidated fs_bsize/fs_fsize superblock fields

Priority LOW 12CWE-400Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-400.

Summary

NanaZip is the 7-Zip derivative intended for the modern Windows experience. Prior to 6.5.1749.0, NanaZip's UFS and FFS image handler in NanaZip.Codecs.Archive.Ufs.cpp validates the superblock block size only against the MINBSIZE lower bound and does not validate the fs_fsize fragment size, allowing attacker-controlled 32-bit fields to flow into indirect-block, directory, and extraction buffer allocations. A tiny crafted UFS image can force multi-gigabyte allocations during open or extraction, causing memory exhaustion or process termination. This issue is fixed in version 6.5.1749.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00159 5th percentileScored 2026-11-07
Fix Fixed NanaZip (M2Team): 6.5.1749.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
M2TeamNanaZipbefore 6.5.1749.06.5.1749.0Patch availableCNA
  • NanaZip VendorM2Team Affected before 6.5.1749.0 Fixed in 6.5.1749.0 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:m2team:nanazip:*:*:*:*:*:*:*:*——M2Team
  • cpe:2.3:a:m2team:nanazip:*:*:*:*:*:*:*:* Versions — — ·M2Team

Remediation

  • Fix · CNA NanaZip (M2Team) Fixed in 6.5.1749.0

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55781

References

Other 3

  • TI-2026-39447 NanaZip: Heap out-of-bounds read in NanaZip SquashFS LZ4 decompressor via unchecked negative return value CVSS 3.1HIGH 7.1
  • TI-2026-32194 NanaZip: Heap out-of-bounds write in NanaZip UFS directory parser CVSS 3.1HIGH 7.1
  • TI-2026-34809 NanaZip: Heap out-of-bounds read in NanaZip AVB hashtree descriptor parser via 32-bit unsigned integer overflow CVSS 3.1MEDIUM 5.4
  • TI-2026-34808 NanaZip: Heap out-of-bounds read in NanaZip AVB property descriptor parser via unsigned integer underflow CVSS 3.1MEDIUM 5.4
  • TI-2026-30733 NanaZip: Unbounded resource consumption in NanaZip littlefs parser via attacker-controlled BlockCount CVSS 3.1MEDIUM 5.5
  • TI-2026-21251 NanaZip has DotNet Single file OOB Heap Read CVSS 4.0MEDIUM 5.2
See all 20 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences