ZEN Load Balancer versions 2.0 and 3.0-rc1 contain a command injection vulnerability in content2-2.cgi. The filelog parameter is passed directly into a backtick-delimited exec() call without sanitation. An authenticated attacker can inject arbitrary shell commands, resulting in remote code execution as the root user. ZEN Load Balancer is the predecessor of ZEVENET and SKUDONET. The affected versions (2.0 and 3.0-rc1) are no longer supported. SKUDONET CE is the current community-maintained successor.