Unauthorized authentication via partial username comparison

Partial string comparison in OpenVPN authentication on affected Siemens routers allows remote attackers to get invalid usernames accepted. The username validator compares only part of an untrusted identity instead of the full value, so a prefix can be treated as a valid username. Reachability requires network access to an enabled OpenVPN service; the reported consequence is invalid-username acceptance, with no reported disclosure or service interruption.