OpenEMR is a free and open source electronic health records and medical practice management application. From 6.0.0 until 8.3.0, interface/globals.php uses the unauthenticated authUser login parameter to populate temp_authuserid and load that account's user_settings before authentication succeeds. Existing usernames can therefore cause an additional database query and may apply visible customized settings, while nonexistent usernames skip that behavior. A remote unauthenticated actor can use timing or page differences to enumerate valid accounts for later credential attacks. This issue is fixed in version 8.3.0.
https://github.com/openemr/openemr/security/advisories/GHSA-rr38-hpxq-wwff
https://github.com/openemr/openemr/releases/tag/v8_3_0
https://github.com/openemr/openemr/pull/13133
https://github.com/openemr/openemr/commit/50f789fad45ada625fe8d0faf0c7a9c15ef52aa5