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PatchSiren cyber security CVE debrief

CVE-2020-3992 VMware CVE debrief

CVE-2020-3992 is a VMware ESXi vulnerability in OpenSLP described by CISA as a use-after-free issue. It was added to the CISA Known Exploited Vulnerabilities catalog on 2021-11-03, indicating confirmed exploitation in the wild. CISA also marks it as having known ransomware campaign use, so ESXi environments should treat it as an urgent remediation item and follow VMware’s update guidance.

Vendor
VMware
Product
ESXi
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

VMware ESXi administrators, virtualization teams, infrastructure security teams, and incident responders responsible for internet-facing or business-critical ESXi hosts should prioritize this CVE.

Technical summary

The official record identifies the flaw as an OpenSLP use-after-free vulnerability in VMware ESXi. CISA’s KEV entry confirms active exploitation and notes known ransomware campaign use. The provided official guidance is to apply updates per vendor instructions; no exploit mechanics are included here.

Defensive priority

Urgent. This is a CISA KEV-listed vulnerability with known ransomware campaign use, so remediation should be prioritized ahead of routine patch cycles.

Recommended defensive actions

  • Apply VMware updates per vendor instructions as soon as possible.
  • Inventory ESXi hosts to confirm which systems are affected and whether they are exposed or high value.
  • Prioritize remediation of externally reachable or production ESXi systems.
  • Review security monitoring for signs of unauthorized access or suspicious activity on ESXi infrastructure.
  • Validate backup, recovery, and incident-response readiness for virtualization hosts.
  • Track the official VMware and CISA guidance for any additional remediation notes.

Evidence notes

This debrief is based on the CISA Known Exploited Vulnerabilities feed entry for CVE-2020-3992 and the official CVE/NVD records linked from that entry. The source metadata states: vendor VMware, product ESXi, vulnerability name ‘VMware ESXi OpenSLP Use-After-Free Vulnerability,’ dateAdded 2021-11-03, dueDate 2022-05-03, and knownRansomwareCampaignUse ‘Known.’

Official resources

CISA added CVE-2020-3992 to the Known Exploited Vulnerabilities catalog on 2021-11-03 and records known ransomware campaign use. No exploit instructions are included.