core/imap/MCIMAPSession.cpp in Canary Mail before 3.22 has Missing SSL Certificate Validation for IMAP in STARTTLS mode.
www.openwall.com/lists/oss-security/2021/02/17/3
apps.apple.com/us/app/canary-mail/id1236045954
census-labs.com/news/2021/02/17/canary-mail-app-missing-certificate-validation-check-on-imap-starttls/
census-labs.com/news/category/advisories/
github.com/canarymail/mailcore2/commit/45acb4efbcaa57a20ac5127dc976538671fce018
www.openwall.com/lists/oss-security/2021/02/17/3