{
    "id": "CVE-2021-28799",
    "published": "2021-05-13 03:15:06",
    "last_modified": "2026-06-17 03:46:53",
    "cvss_score": "10.0",
    "cvss_severity": "CRITICAL",
    "cvss_version": "3.1",
    "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
    "cwe": "CWE-285",
    "description": "An improper authorization vulnerability has been reported to affect QNAP NAS running HBS 3 (Hybrid Backup Sync. ) If exploited, the vulnerability allows remote attackers to log in to a device. This issue affects: QNAP Systems Inc. HBS 3 versions prior to v16.0.0415 on QTS 4.5.2; versions prior to v3.0.210412 on QTS 4.3.6; versions prior to v3.0.210411 on QTS 4.3.4; versions prior to v3.0.210411 on QTS 4.3.3; versions prior to v16.0.0419 on QuTS hero h4.5.1; versions prior to v16.0.0419 on QuTScloud c4.5.1~c4.5.4. This issue does not affect: QNAP Systems Inc. HBS 2 . QNAP Systems Inc. HBS 1.3 .",
    "epss_score": "0.78250",
    "epss_percentile": "0.99566",
    "kev": 1,
    "kev_due": "2022-04-21",
    "has_exploit": 0,
    "updated_at": "2026-09-26 18:27:29",
    "priority": {
        "rank": 1,
        "label": "Patch first",
        "why": "On CISA KEV — known exploited in the wild, due 2022-04-21."
    },
    "products": [
        {
            "vendor": "qnap",
            "product": "hybrid_backup_sync"
        },
        {
            "vendor": "qnap",
            "product": "qts"
        },
        {
            "vendor": "qnap",
            "product": "quts_hero"
        },
        {
            "vendor": "qnap",
            "product": "qutscloud"
        }
    ],
    "kev_detail": {
        "cve_id": "CVE-2021-28799",
        "date_added": "2022-03-31",
        "due_date": "2022-04-21",
        "vendor": "QNAP",
        "product": "Network Attached Storage (NAS)",
        "name": "QNAP NAS Improper Authorization Vulnerability",
        "ransomware": 1
    },
    "exploits": [],
    "refs_list": [
        "https://www.qnap.com/en/security-advisory/QSA-21-13",
        "https://www.qnap.com/en/security-advisory/QSA-21-13",
        "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-28799"
    ]
}