{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2021-28799",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-28799",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2021-05-13T02:55:13.827Z",
    "updatedAt": "2025-10-21T23:25:45.551Z",
    "importedAt": "2026-10-24T01:56:26.894Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "Improper Authorization Vulnerability in HBS 3 (Hybrid Backup Sync)",
      "summary": "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 .",
      "affected": [
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 3",
          "platforms": [
            "QTS 4.5.2"
          ],
          "versions": [
            {
              "version": "unspecified",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "v16.0.0415"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 3",
          "platforms": [
            "QTS 4.3.6"
          ],
          "versions": [
            {
              "version": "unspecified",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "v3.0.210412"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 3",
          "platforms": [
            "QTS 4.3.4"
          ],
          "versions": [
            {
              "version": "unspecified",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "v3.0.210411"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 3",
          "platforms": [
            "QTS 4.3.3"
          ],
          "versions": [
            {
              "version": "unspecified",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "v3.0.210411"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 3",
          "platforms": [
            "QuTS hero h4.5.1"
          ],
          "versions": [
            {
              "version": "unspecified",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "v16.0.0419"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 3",
          "platforms": [
            "QuTScloud c4.5.1~c4.5.4"
          ],
          "versions": [
            {
              "version": "unspecified",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "v16.0.0419"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 2",
          "versions": [
            {
              "version": "all versions",
              "status": "unaffected"
            }
          ]
        },
        {
          "vendor": "QNAP Systems Inc.",
          "product": "HBS 1.3",
          "versions": [
            {
              "version": "all versions",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  }
}