CVE-2026-55781

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Source

https://cve.org/CVERecord?id=CVE-2026-55781

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55781.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-55781

Aliases

GHSA-m34h-jf84-m74h

Published

2026-07-10T16:50:24.371Z

Modified

2026-07-15T19:00:09.282124Z

Severity

2.4 (Low) CVSS_V4 - CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N CVSS Calculator

Summary

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

Details

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.

Database specific

{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-400",
        "CWE-789"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55781.json"
}

References

Affected packages

Git / github.com/m2team/nanazip

Affected ranges

Type

GIT

Repo

https://github.com/m2team/nanazip

Events

Introduced

Fixed

6415b6bff70bc9c486b49cbbc1982724c67f8338

Fixed

1eaba2b09dfd3c78dab55e629ad4024d97d03567

Database specific

{
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "6.5.1749.0"
        }
    ]
}

Affected versions

1.*

1.0

1.0-Preview1

1.0-Preview2

1.0-Preview3

1.0-Preview4

1.1

1.1+ServicingUpdate1-Preview1

1.1+ServicingUpdate1-Preview2

1.1+ServicingUpdate1-Preview3

1.1-Preview1

1.1-Preview2

1.1-Preview2-Update1

1.2

1.2-Preview4

1.2.253

2.*

2.0.313

2.0.376

2.0.396

2.0.450

2.1.451

3.*

3.0.1000.0

3.0.756

3.0.996

3.1.1080.0

3.5.1000.0

3.5.996

5.*

5.0.1188.0

5.0.1215.0

5.0.1243.0

5.0.1250.0

5.0.1252.0

5.0.1263.0

5.1.1252.0

5.1.1263.0

6.*

6.0.1461.0

6.0.1621.0

6.0.1630.0

6.0.1632.0

6.5.1638.0

6.5.1742.0

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55781.json"

vanir_signatures

[
    {
        "id": "CVE-2026-55781-19f0a4da",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/m2team/nanazip/commit/6415b6bff70bc9c486b49cbbc1982724c67f8338",
        "deprecated": false,
        "digest": {
            "threshold": 0.9,
            "line_hashes": [
                "118052540696771222209132468916937803639",
                "272894522132223952993495107818370126798",
                "287648923571818377379354665354508541743",
                "169083364205515581401815706229875531520",
                "4478985626960547348204276775598263002",
                "201442352688857167118090112355177058577",
                "100534595045179556551861417123493840653",
                "316548347891118170757392578328443538202",
                "77866485700562332812866987849356877498",
                "84045664844161802110168112814257563741",
                "84234795926193863602690993344021018273",
                "252791722556085096503431655344144795150",
                "125351551990459367755236291301544837060",
                "275407133164412933563051785168203958769",
                "228918824311046596695721892998041907081",
                "137813465584218393297438951144246752760",
                "100295060892212654021857950281333134874",
                "257128502687205643115193506200346353395"
            ]
        },
        "target": {
            "file": "NanaZip.Codecs/NanaZip.Codecs.Archive.Ufs.cpp"
        }
    }
]

vanir_signatures_modified

"2026-07-15T19:00:09Z"