Softaculous Virtualizor before 3.2.9 (Patch 9) and 3.0.0 contains an OS command injection vulnerability in the billing module handler that allows unauthenticated remote attackers to execute arbitrary commands as root by bypassing authentication through specific parameter combinations. Attackers can deserialize a crafted billing_data POST field and inject shell payloads through the uid field, which is passed unmodified to proc_open() via vexec(), yielding complete control of the host and all managed VPS instances.