{"cve":{"cve_id":"CVE-2021-28809","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.15678,"epss_percentile":0.96426,"epss_as_of":"2026-06-23","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","published_at":"2021-07-08T07:40:12.294000Z","last_modified_at":null,"cvss_v3_score":9.8,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_v3_severity":"CRITICAL","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-284","CWE-306","CWE-749"],"nvd_references":["https://www.qnap.com/en/security-advisory/qsa-21-19","https://www.zerodayinitiative.com/advisories/ZDI-21-783/"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:15:26.101164Z"},"effective_severity":"CRITICAL","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"H","value_label":"High"},{"metric":"I","name":"Integrity","value":"H","value_label":"High"},{"metric":"A","name":"Availability","value":"H","value_label":"High"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"qnap-systems-inc.","vendor_name":"QNAP Systems Inc.","product_slug":"hbs-3","product_name":"HBS 3","version_start":"unspecified","version_start_inclusive":true,"version_end":"v3.0.210507","version_end_inclusive":false,"cpe23_uri":"cve5:qnap-systems-inc.:hbs-3:unspecified:v3.0.210507"},{"vendor_slug":"qnap-systems-inc.","vendor_name":"QNAP Systems Inc.","product_slug":"hbs-3","product_name":"HBS 3","version_start":"unspecified","version_start_inclusive":true,"version_end":"v3.0.210506","version_end_inclusive":false,"cpe23_uri":"cve5:qnap-systems-inc.:hbs-3:unspecified:v3.0.210506"}],"exploit_refs":[],"news":[],"references":[{"url":"https://www.qnap.com/en/security-advisory/qsa-21-19","source_type":"MISC","tags":[]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-783/","source_type":"VENDOR_ADVISORY","tags":["advisory"]}],"timeline":[{"type":"published","at":"2021-07-08T07:40:12.294000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:18:04.076611Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:18:04.076611Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:18:04.076611Z","label":"CVSS score revised","source":"cvelistv5"}]}