VMware vCenter Server Syslog Service Directory Traversal Remote Code Execution Vulnerability (CVE-2026-59310)

1. Apply Official Security Patches

Refer to the Broadcom Support Portal and apply the designated security updates for your specific vCenter Server deployment version immediately.

2. Temporary Mitigation & Workarounds

If patching cannot be performed immediately, implement the following network-level access controls:

• Restrict Syslog Port Access: Block external internet access to Syslog ports (UDP/TCP 514) and the vCenter management interface (HTTPS 443).
• Firewall (iptables) Configuration Example:

  # Allow Syslog traffic only from a trusted internal SIEM/collector (e.g., 10.0.0.100)
  iptables -A INPUT -p udp -s 10.0.0.100 --dport 514 -j ACCEPT
  iptables -A INPUT -p tcp -s 10.0.0.100 --dport 514 -j ACCEPT
  # Drop all other Syslog traffic
  iptables -A INPUT -p udp --dport 514 -j DROP
  iptables -A INPUT -p tcp --dport 514 -j DROP

3. Compromise Assessment & Monitoring

• Inspect vCenter directory structures (such as /usr/lib/vmware-sso/ or /storage/log/) for unauthorized file creations or modifications.
• Update IDS/IPS signatures to detect inbound network traffic containing directory traversal sequences (../ or ..\) targeting port 514.

CVE-2026-59310 is a critical Directory Traversal vulnerability (CWE-22) residing within the built-in Syslog server component of VMware vCenter Server.

By sending specially crafted Syslog messages or network requests, an unauthenticated attacker can bypass input validation mechanisms to traverse directories and write arbitrary files to the underlying filesystem. This capability allows attackers to drop web shells or overwrite critical system scripts, leading to Remote Code Execution (RCE) with administrative privileges on the vCenter Server appliance.

With a CVSS 3.1 score of 9.8 (Critical) and active exploitation confirmed in the wild (CISA KEV listed), this vulnerability poses an immediate threat. Threat intelligence reports indicate active targeting by advanced persistent threat (APT) actors, making immediate remediation mandatory.