OfflineIMAP before 8.0.3 trusts the server with their STARTTLS capability prior to authentication, which allows STRIPTLS/man-in-the-middle attacks, taking over the connection and extracting account credentials in cleartext.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:HI:LA:N6.5/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:NOther