In Dovecot before 2.3.10.1, remote unauthenticated attackers can crash the lmtp or submission process by sending mail with an empty localpart.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:NA:L5.3/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L