This might be proprietary software.

#Vulnerabilities 3
Date Id Summary Products Score Patch Annotated
2020-01-29 CVE-2020-7247 smtp_mailaddr in smtp_session.c in OpenSMTPD 6.6, as used in OpenBSD 6.6 and other products, allows remote attackers to execute arbitrary commands as root via a crafted SMTP session, as demonstrated by shell metacharacters in a MAIL FROM field. This affects the "uncommented" default configuration. The issue exists because of an incorrect return value upon failure of input validation. Debian_linux, Opensmtpd 9.8
2017-10-16 CVE-2015-7687 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. Fedora, Opensmtpd 9.8
2014-05-27 CVE-2013-2125 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. Opensmtpd N/A