libreswan: null-pointer dereference by sending two IKEv2 packets

In Libreswan 3.27 an assertion failure can lead to a pluto IKE daemon restart. An attacker can trigger a NULL pointer dereference by initiating an IKEv2 IKESAINIT exchange, followed by a bogus INFORMATIONAL exchange instead of the normallly expected IKEAUTH exchange. This affects...