Use-after-free vulnerability in OpenSMTPD before 5.7.2 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via vectors involving req_ca_vrfy_smtp and req_ca_vrfy_mta.
OpenSMTPD before 5.3.2 does not properly handle SSL sessions, which allows remote attackers to cause a denial of service (connection blocking) by keeping a connection open.