isakmpd payload handling denial-of-service vulnerabilities

Numerous errors in isakmpd's input packet validation lead to denial-of-service vulnerabilities. From the Rapid7 advisory:

The ISAKMP packet processing functions in OpenBSD's isakmpd daemon contain multiple payload handling flaws that allow a remote attacker to launch a denial of service attack against the daemon.

Carefully crafted ISAKMP packets will cause the isakmpd daemon to attempt out-of-bounds reads, exhaust available memory, or loop endlessly (consuming 100% of the CPU).

[source]