It was discovered that OpenLDAP did not properly check forwarded authentication failures when using a slave server and chain overlay. If OpenLDAP were configured in this manner, an attacker could bypass authentication checks by sending an invalid password to a slave server. It was discovered that OpenLDAP did not properly perform authentication checks to the rootdn when using the back-ndb backend. An attacker could exploit this to access the directory by sending an arbitrary password. Ubuntu does not ship OpenLDAP with back-ndb support by default. This issue did not affect Ubuntu 8.04 LTS. It was discovered that OpenLDAP did not properly validate modrdn requests. An unauthenticated remote user could use this to cause a denial of service via application crash