{"id":"CVE-2021-28809","aliases":["EUVD-2021-15465","GHSA-fwr8-wff7-fmxw"],"status":"published","title":"Missing Authentication for Critical Function in RTRR Server in HBS3","description":"An improper access control vulnerability has been reported to affect certain legacy versions of HBS 3. If exploited, this vulnerability allows attackers to compromise the security of the operating system.QNAP have already fixed this vulnerability in the following versions of HBS 3: QTS 4.3.6: HBS 3 v3.0.210507 and later QTS 4.3.4: HBS 3 v3.0.210506 and later QTS 4.3.3: HBS 3 v3.0.210506 and later","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.16093,"percentile":0.96949,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-284","CWE-306","CWE-749"],"published":"2021-07-08T07:40:12Z","modified":"2026-06-17T03:46:54Z","products":[{"vendor":"qnap","product":"hybrid_backup_sync"},{"vendor":"qnap systems inc.","product":"hbs 3"}],"references":[{"url":"https://www.qnap.com/en/security-advisory/qsa-21-19","tags":["x_refsource_MISC","x_transferred","Vendor Advisory"]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-783/","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","VDB Entry"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-28809"},{"url":"https://github.com/advisories/GHSA-fwr8-wff7-fmxw"}],"sources":{"cve":[{"id":"CVE-2021-28809","title":"Missing Authentication for Critical Function in RTRR Server in HBS3","description":"An improper access control vulnerability has been reported to affect certain legacy versions of HBS 3. If exploited, this vulnerability allows attackers to compromise the security of the operating system.QNAP have already fixed this vulnerability in the following versions of HBS 3: QTS 4.3.6: HBS 3 v3.0.210507 and later QTS 4.3.4: HBS 3 v3.0.210506 and later QTS 4.3.3: HBS 3 v3.0.210506 and later","status":"published","published":"2021-07-08T07:40:12.294Z","modified":"2024-09-17T00:36:54.377Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-284","CWE-306","CWE-749"],"updated_at":"2026-11-02T14:33:08.811269Z"}],"euvd":[{"id":"EUVD-2021-15465","description":"An improper access control vulnerability has been reported to affect certain legacy versions of HBS 3. If exploited, this vulnerability allows attackers to compromise the security of the operating system.QNAP have already fixed this vulnerability in the following versions of HBS 3: QTS 4.3.6: HBS 3 v3.0.210507 and later QTS 4.3.4: HBS 3 v3.0.210506 and later QTS 4.3.3: HBS 3 v3.0.210506 and later","status":"published","published":"2021-07-08T07:40:12Z","modified":"2024-09-17T00:36:54Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-03T00:28:57.378482Z"}],"ghsa":[{"id":"GHSA-fwr8-wff7-fmxw","title":"An improper access control vulnerability has been reported to affect certain legacy versions of...","description":"An improper access control vulnerability has been reported to affect certain legacy versions of HBS 3. If exploited, this vulnerability allows attackers to compromise the security of the operating system.QNAP have already fixed this vulnerability in the following versions of HBS 3: QTS 4.3.6: HBS 3 v3.0.210507 and later QTS 4.3.4: HBS 3 v3.0.210506 and later QTS 4.3.3: HBS 3 v3.0.210506 and later","status":"published","published":"2022-05-24T19:07:18Z","modified":"2023-01-30T05:00:39Z","cwes":["CWE-284"],"updated_at":"2026-11-02T14:46:14.926249Z"}],"nvd":[{"id":"CVE-2021-28809","description":"An improper access control vulnerability has been reported to affect certain legacy versions of HBS 3. If exploited, this vulnerability allows attackers to compromise the security of the operating system.QNAP have already fixed this vulnerability in the following versions of HBS 3: QTS 4.3.6: HBS 3 v3.0.210507 and later QTS 4.3.4: HBS 3 v3.0.210506 and later QTS 4.3.3: HBS 3 v3.0.210506 and later","status":"published","published":"2021-07-08T08:15:07.663Z","modified":"2026-06-17T03:46:54.16Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"secondary"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"},{"version":"2.0","score":10,"vector":"AV:N/AC:L/Au:N/C:C/I:C/A:C","level":"high","assessor":"primary"}],"cwes":["CWE-284","CWE-306","CWE-749"],"updated_at":"2026-11-02T14:06:55.259633Z"}]}}