ispdbservice.cpp in KDE Kmail before 6.2.0 allows man-in-the-middle attackers to trigger use of an attacker-controlled mail server because cleartext HTTP is used for a URL such as http://autoconfig.example.com or http://example.com/.well-known/autoconfig for retrieving the configuration. This is related to kmail-account-wizard.
https://kde.org/announcements/megarelease/6/
https://invent.kde.org/pim/kmail/-/tags
https://invent.kde.org/pim/kmail-account-wizard/-/commit/9784f5ab41c3aff435d4a88afb25585180a62ee4