Affected versions of Atlassian Jira Server and Data Center allow an unauthenticated user to enumerate users via an Information Disclosure vulnerability in the /ViewUserHover.jspa endpoint.

This vulnerability was discovered by Mikhail Klyuchnikov of Positive Technologies.

Affected versions:

• version < 7.13.16
• 8.0.0 ≤ version < 8.5.7
• 8.6.0 ≤ version < 8.12.0

Fixed versions:

• 7.13.16
• 8.5.7
• 8.12.0