The commit diff shows the vulnerability stemmed from directly passing the message to syslog() as the format string argument. The original code used 'syslog(priority, message)' which exposes a classic format string vulnerability when 'message' contains user-controlled content. The patch explicitly adds a static '%s' format string as the second parameter, making 'message' a safe argument rather than a format template. The CWE-134 classification and advisory descriptions confirm this was a format string misuse in the syslog function call.