CVE-2026-55781PoC

LOWCVSS 2.4 · LOW

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

Patch affected systems immediately
Hunt for exploitation attempts and persistence artifacts
Increase monitoring for publicly documented tradecraft

Recommended action window: High priority (within 72h)

NVD description

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.

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2.0/ 10 priority

Sources & remediation

Other references

Weakness type (CWE)

CWE-400CWE-789

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

NONE

Threat summary

Public PoC is present in monitored signal
Patch or workaround signal is available
1 mentions across 1 observed day

What's happening

PoC mentioned or linked in 1 signal
Patch or workaround mentioned in 1 signal
Technical details provided in 1 signal
1 total mentions across 1 day

Deep dive

Activity timeline1 mentions / 1d

Signal classification1 categories

PoC

1100.0%

Referenced assets1 URL

By indicator

https://github.com/g17hubH4ck/CVE-2026-55781-poc

Full discourse1 post

Rıdvan Yağlı@ridvanyagli46d
PoC
NanaZip'in UFS parser'ındaki CVE-2026-55781 için PoC yayınlandı. Saldırgan tarafından kontrol edilebilen fs_bsize alanının yeterince sınırlandırılmaması, hazırlanmış bir UFS imajının işlenmesi sırasında aşırı bellek tahsisine ve DoS'a yol açabiliyor. Etkilenen sürümler: NanaZip <= 6.5.1742.0 Düzeltilen sürüm: 6.5.1749.0 PoC: https://github.com/g17hubH4ck/CVE-2026-55781-poc
Post summary
A Proof of Concept (PoC) for CVE-2026-55781 in NanaZip's UFS parser has been published, demonstrating a DoS via uncontrolled fs_bsize field leading to excessive memory allocation. Affected versions up to 6.5.1742.0, fixed in 6.5.1749.0.
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