{"cve":{"cve_id":"CVE-2021-21985","is_kev":true,"kev_date_added":"2021-11-03","kev_vendor_project":"VMware","kev_product":"vCenter Server","kev_vulnerability_name":"VMware vCenter Server Improper Input Validation Vulnerability","kev_short_description":"VMware vSphere Client contains an improper input validation vulnerability in the Virtual SAN Health Check plug-in, which is enabled by default in vCenter Server, which allows for remote code execution.","kev_required_action":"Apply updates per vendor instructions.","kev_due_date":"2021-11-17","kev_known_ransomware":true,"kev_notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-21985","kev_cwes":["CWE-20","CWE-470","CWE-918"],"epss_score":0.99999,"epss_percentile":0.99992,"epss_as_of":"2026-06-23","description":"The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server. A malicious actor with network access to port 443 may exploit this issue to execute commands with unrestricted privileges on the underlying operating system that hosts vCenter Server.","published_at":"2021-05-26T14:04:30Z","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-20","CWE-470","CWE-918"],"nvd_references":["https://www.vmware.com/security/advisories/VMSA-2021-0010.html","http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.html","http://packetstormsecurity.com/files/163487/VMware-vCenter-Server-Virtual-SAN-Health-Check-Remote-Code-Execution.html"],"vuln_status":null,"trending_score":0.6099982,"is_trending":true,"has_trended":true,"trended_number_one":false,"trending_peak_score":0.6099982,"trending_peak_rank":43,"started_trending_at":"2026-06-29T02:30:27.366045Z","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","ransomware","poc","trending","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-2021-21985.yaml","title":"VMware vSphere Client (HTML5) - Remote Code Execution","author":"D0rkerDevil","disclosed_at":null}],"news":[],"references":[{"url":"https://www.vmware.com/security/advisories/VMSA-2021-0010.html","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.html","source_type":"EXPLOIT","tags":["exploit"]},{"url":"http://packetstormsecurity.com/files/163487/VMware-vCenter-Server-Virtual-SAN-Health-Check-Remote-Code-Execution.html","source_type":"EXPLOIT","tags":["exploit"]}],"timeline":[{"type":"published","at":"2021-05-26T14:04:30Z","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"},{"type":"started_trending","at":"2026-06-29T02:30:27.366045Z","label":"Started trending","source":null}]}