CVE-2018-5739: ISC Kea 1.4.0 failure to release memory may exhaust system resources

Hook/Hook Point – used interchageably, this is a point in the code at which a call to user functions is made. Each hook has a name and each hook can have any number (including 0) of user functions attached to it. Store leases and host reservations in a MySQL, PostgreSQL or Cassandra database rather than a text file.

official document for reference: https://kb.isc.org/article/AA-01626