The issue causes libreswan to restart under some IKEv2 retransmit scenarios when a connection is configured to use PreSharedKeys (authby=secret) and the connection cannot find a matching configured secret. This can lead to repeated crashes and a Denial of Service, especially when such a connection is automatically added on startup using the auto= keyword. The vulnerability is related to the use of PreSharedKeys for creating the AUTH payload in IKE AUTH Exchange, allowing a remote attacker to perform a Denial of Service attack.