Enonic has just released Enonic XP 6.5.4 to fix the bug that cause Enonic XP to fail on the latest update of Java 8. Version 6.5.4 will work on any update of Java 8, but we always recommend using the latest version, when possible. 
The bug is listed in the release list on Github: https://github.com/enonic/xp/releases/tag/v6.5.4
The release can be downloaded from our repository: http://repo.enonic.com/public/com/enonic/xp/distro/6.5.4/ - and the latest release is always available on our web-pages: https://enonic.com/downloads