{"id":"CVE-2021-28799","aliases":[],"url":"https://o3.security/vulnerability/CVE-2021-28799","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…","details":"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 .","published":"2021-05-13T02:55:13.827Z","modified":"2025-10-21T23:25:45.551Z","cvss":{"score":10,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"},"epss":{"score":0.7825,"percentile":0.99543,"asOf":"2026-08-27"},"cisaKev":{"dateAdded":"2022-03-31","dueDate":"2022-04-21","knownRansomwareCampaignUse":true},"exploitsKnown":3,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://www.qnap.com/en/security-advisory/QSA-21-13"},{"type":"WEB","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-28799"}],"provenance":{"sources":["OSV.dev","NVD","CISA KEV","FIRST.org (EPSS)"],"lastVerified":"2025-10-21T23:25:45.551Z"}}