Fixed: Potential exploit in the OCB2 encryption (#4227)

Fixed: Added missing UserKDFIterations field to UserInfo => Prevents getRegistration() from failing with enumerator out of range error (#3835)

Fixed: Segmentation fault during murmur shutdown (#3938)

Fixed: Possibility to circumvent max user-count in channel (#3880)
Fixed: Rate-limit implementation susceptible to time-underflow (#4004)
Fixed: OpenSSL error 140E0197 with Qt >= 5.12.2 (#4032)
Fixed: VersionCheck for SQL for when to use the WAL feature (#4163)
Fixed: Wrong database encoding that could lead to server-crash (#4220)
Fixed: DB crash due to primary key violation (now performs “UPSERT” to avoid this) (#4105)
Improved: The fields in the Version ProtoBuf message are now size-restricted in order to avoid attacks that can render another client unresponsive (#4101)