GHSA-3m37-hwq6-jrj8: Zulip: Custom profile fields can be read by logged-out visitors in organization with web-public channels

Zulip is an open-source team collaboration tool. From 11.0 until 12.2, organizations with web-public channels enabled exposed the GET /json/users endpoint to logged-out spectators, and a missing access-control check allowed includecustomprofilefields=true to return every user's custom profile field values in addition to the documented limited directory data. This exposed those custom profile field values to unauthenticated visitors. This issue is fixed in version 12.2.