The /rest/api/1.0/render resource in Jira Server and Data Center before version 8.5.13, from version 8.6.0 before version 8.13.5, and from version 8.14.0 before version 8.15.1 allows remote anonymous attackers to determine if a username is valid or not via a missing permissions check.
The membersOf JQL search function in Jira Server and Data Center before version 8.5.13, from version 8.6.0 before version 8.13.5, and from version 8.14.0 before version 8.15.1 allows remote anonymous attackers to determine if a group exists & members of groups if they are assigned to publicly visible issue field.
The MessageBundleWhiteList class of atlassian-gadgets before version 4.2.37, from version 4.3.0 before 4.3.14, from version 4.3.2.0 before 4.3.2.4, from version 4.4.0 before 4.4.12, and from version 5.0.0 before 5.0.1 allowed unexpected DNS lookups and requests to arbitrary services as it incorrectly obtained application base url information from the executing http request which could be attacker controlled.
Affected versions of Atlassian Jira Server and Data Center allow remote attackers to view the metadata of boards they should not have access to via an Insecure Direct Object References (IDOR) vulnerability. The affected versions are before version 8.5.10, and from version 8.6.0 before 8.13.2.