Atlassian and Contegix (who together make the Hibernate JIRA possible) have found evidence that the Hibernate JIRA has been compromised through the recent JIRA exploit affecting numerous Open Source JIRA instances.
At this time they are still investigating and analyzing to determine the extent of the compromise. Specifically it is unknown yet whether passwords or user data in general were accessed.
In the meantime, Contegix will be upgrading the JIRA software. As a protection measure, all passwords have been reset. On logging back in you will be forced to reset your password via email (look for the Can't access your account?
link next to the Log In button).