So:
The updates have been made available by Citrix on last wednesday
We've published update candidates for testers on thursday
Updates for XCP-ng 7.6 have been made available to everyone yesterday
Updates for XCP-ng 7.5 have been made available to everyone this morning
Blog post published: https://xcp-ng.org/blog/2019/03/12/xcp-ng-security-bulletin-vulnerabilities-pv-guests/