xrdp: Heap buffer overflow in xrdp_sec_process_logon_info() via incorrect g_strncat length calculation

xrdp is an open source RDP server. Versions through 0.10.5 contain a heap-based buffer overflow vulnerability in its logon processing. In environments where domain_user_separator is configured in xrdp.ini, an unauthenticated remote attacker can send a crafted, excessively long username and domain name to overflow the internal buffer. This can corrupt adjacent memory regions, potentially leading to a Denial of Service (DoS) or unexpected behavior. The domain_name_separator directive is commented out by default, systems are not affected by this vulnerability unless it is intentionally configured. This issue has been fixed in version 0.10.6.