A path traversal vulnerability exists in Riverbed SteelHead VCX appliances (confirmed in VCX255U 9.6.0a) due to improper input validation in the log filtering functionality exposed via the management web interface. An authenticated attacker can exploit this flaw by submitting crafted filter expressions to the log_filter endpoint using the filterStr parameter. This input is processed by a backend parser that permits execution of file expansion syntax, allowing the attacker to retrieve arbitrary system files via the log viewing interface.