{"cve":{"cve_id":"CVE-2021-20090","is_kev":true,"kev_date_added":"2021-11-03","kev_vendor_project":"Arcadyan","kev_product":"Buffalo Firmware","kev_vulnerability_name":"Arcadyan Buffalo Firmware Path Traversal Vulnerability","kev_short_description":"Arcadyan Buffalo firmware contains a path traversal vulnerability that could allow unauthenticated, remote attackers to bypass authentication and access sensitive information. This vulnerability affects multiple routers across several different vendors.","kev_required_action":"Apply updates per vendor instructions.","kev_due_date":"2021-11-17","kev_known_ransomware":false,"kev_notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-20090","kev_cwes":["CWE-22"],"epss_score":0.99983,"epss_percentile":0.99981,"epss_as_of":"2026-06-23","description":"A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.","published_at":"2021-04-29T00:00:00Z","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":"active","ssvc_automatable":true,"ssvc_technical_impact":"total","cwes":["CWE-22"],"nvd_references":["https://www.tenable.com/security/research/tra-2021-13","https://www.kb.cert.org/vuls/id/914124","https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/"],"vuln_status":null,"trending_score":0.6099694,"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":"2026-06-24T00:09:31.350578Z","updated_at":"2026-06-29T02:30:27.550645Z"},"effective_severity":"CRITICAL","badges":["kev","poc","epss"],"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":[],"exploit_refs":[{"source":"nuclei","kind":"nuclei","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-20090.yaml","title":"Buffalo WSR-2533DHPL2 - Path Traversal","author":"gy741","disclosed_at":null}],"news":[],"references":[{"url":"https://www.tenable.com/security/research/tra-2021-13","source_type":"MISC","tags":[]},{"url":"https://www.kb.cert.org/vuls/id/914124","source_type":"MISC","tags":[]},{"url":"https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/","source_type":"MISC","tags":[]}],"timeline":[{"type":"published","at":"2021-04-29T00:00:00Z","label":"CVE published","source":null},{"type":"cisa_reported","at":"2021-11-03T00:00:00Z","label":"Added to CISA KEV catalog","source":"kev"},{"type":"poc_available","at":"2026-06-24T00:29:48.638073Z","label":"Public PoC available","source":"nuclei"},{"type":"ssvc_changed","at":"2026-06-24T00:31:36.955378Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-06-24T00:31:36.955378Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-06-24T00:31:36.955378Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"cvss_changed","at":"2026-06-24T00:31:36.955378Z","label":"CVSS score revised","source":"vulnrichment"},{"type":"cvss_changed","at":"2026-06-24T00:31:36.955378Z","label":"CVSS score revised","source":"vulnrichment"},{"type":"cvss_changed","at":"2026-06-24T00:31:36.955378Z","label":"CVSS score revised","source":"vulnrichment"}]}