cPanel Urges Users to Patch ConfigServer Firewall Remote Code Execution Flaw
cPanel urges administrators to patch CVE-2026-65638, a flaw letting unauthenticated attackers run commands through ConfigServer Firewall's MESSENGER service; update to CSF 16.30.
CVE-2026-65638 in ConfigServer Security & Firewall (CSF) 14.00–16.29 allows unauthenticated remote attackers to execute arbitrary commands via the MESSENGER service, which is exposed only when MESSENGER is enabled and a reCAPTCHA secret has been configured. Exploitation yields command execution under the unprivileged CSF service account, providing a foothold for reconnaissance, data access, or lateral movement on internet-facing cPanel/WHM hosting infrastructure. CSF 16.30 or later fixes the issue; disabling MESSENGER in /etc/csf/csf.conf and restarting csf and lfd is a temporary mitigation.