An out-of-bounds memory read flaw was found in the way 389-ds-base handled certain LDAP search filters, affecting all versions including 1.4.x. A remote, unauthenticated attacker could potentially use this flaw to make ns-slapd crash via a specially crafted LDAP request, thus resulting in denial of service.
https://pagure.io/389-ds-base/issue/49545
https://lists.debian.org/debian-lts-announce/2018/07/msg00018.html
https://bugzilla.redhat.com/show_bug.cgi?id=1537314
https://access.redhat.com/errata/RHSA-2018:0515