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Is your VMware ESXi server safe from the latest ransomware attacks?
Critical Security Advisory: Exposed VMware ESXi Servers Face Ransomware
CERT-Bund issued a severe warning in late January 2026 regarding network security. A recent scan identified 2,500 VMware ESXi servers in Germany accessible directly via the public internet. This configuration violates standard security protocols. Concurrently, confirmed reports indicate ransomware groups are actively targeting these exposed instances using a known vulnerability, CVE-2025-22225.
The Risk of Public Exposure
The core issue lies in the accessibility of the management interfaces. These interfaces control the virtual infrastructure and should never face the open internet. CERT-Bund notified network operators repeatedly over two years, yet the warnings often go unheeded.
The statistics regarding these 2,500 servers are alarming:
- 60% run outdated versions no longer supported by the manufacturer.
- 31% run current versions but lack critical security patches.
This negligence creates a massive attack surface. Hackers can easily locate these servers through simple network scans.
Active Exploitation of CVE-2025-22225
Ransomware operators have shifted tactics to exploit specific, unpatched vulnerabilities. CISA warns that attackers are leveraging CVE-2025-22225. This critical flaw allows a “sandbox escape,” enabling malicious code to break out of a constrained environment and compromise the host system.
While this vulnerability has fueled Zero-Day attacks previously, Broadcom released the fix in March 2025. The manufacturer simultaneously patched related flaws (CVE-2025-22224 and CVE-2025-22226) for VMware ESXi, Workstation, and Fusion.
Immediate Remediation Steps
Admins managing VMware environments must act immediately. The continued exploitation of a year-old vulnerability indicates a failure in patch management protocols.
- Isolate Interfaces: Remove management interfaces from public internet access immediately. Use VPNs or restricted internal networks for administration.
- Apply Updates: Install the March 2025 updates from Broadcom to resolve CVE-2025-22225.
- Verify vCenter: Check systems for CVE-2024-37079, another vulnerability CISA flagged as a high-priority target.