dovecot does not properly validate client certificates. An attacker who is in possession of a valid certificate but without a username is able to impersonate other users by abusing the vulnerability.
lists.opensuse.org/opensuse-security-announce/2019-04/msg00067.html
lists.opensuse.org/opensuse-security-announce/2019-04/msg00067.html
access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.1_release_notes/
access.redhat.com/errata/RHSA-2019:3467
access.redhat.com/security/updates/classification/#moderate
bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3814
bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3814
lists.fedoraproject.org/archives/list/[email protected]/message/4XLI55NGRDTGMVOPYFCPPFNPA5VKYSSY/
lists.fedoraproject.org/archives/list/[email protected]/message/4XLI55NGRDTGMVOPYFCPPFNPA5VKYSSY/
security.gentoo.org/glsa/201904-19
security.gentoo.org/glsa/201904-19
www.dovecot.org/list/dovecot/2019-February/114575.html
www.dovecot.org/list/dovecot/2019-February/114575.html