CVE-2020-12100: Parsing mails with a large number of MIME parts could
      have resulted in excessive CPU usage or a crash due to running out of
      stack memory.
    CVE-2020-12673: Dovecot's NTLM implementation does not correctly check
      message buffer size, which leads to reading past allocation which can
      lead to crash.
    CVE-2020-10967: lmtp/submission: Issuing the RCPT command with an
      address that has the empty quoted string as local-part causes the lmtp
      service to crash.
    CVE-2020-12674: Dovecot's RPA mechanism implementation accepts
      zero-length message, which leads to assert-crash later on.