The Portal Security module in Liferay Portal 7.2.1 and earlier, and Liferay DXP 7.0 before fix pack 90, 7.1 before fix pack 17 and 7.2 before fix pack 5 does not correctly import users from LDAP, which allows remote attackers to prevent a legitimate user from authenticating by attempting to sign in as a user that exist in LDAP.