An OpenLDAP server could potentially be made to crash if it received specially crafted network traffic from an authenticated user.

=========================================================================Ubuntu Security Notice USN-1266-1
November 17, 2011

openldap vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 11.10
- Ubuntu 11.04
- Ubuntu 10.10
- Ubuntu 10.04 LTS

Summary:

An OpenLDAP server could potentially be made to crash if it received
specially crafted network traffic from an authenticated user.

Software Description:
- openldap: OpenLDAP utilities

Details:

It was discovered that slapd contained an off-by-one error. An
authenticated attacker could potentially exploit this by sending a
crafted crafted LDIF entry containing an empty postalAddress.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 11.10:
  slapd                           2.4.25-1.1ubuntu4.1

Ubuntu 11.04:
  slapd                           2.4.23-6ubuntu6.1

Ubuntu 10.10:
  slapd                           2.4.23-0ubuntu3.7

Ubuntu 10.04 LTS:
  slapd                           2.4.21-0ubuntu5.6

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-1266-1
  CVE-2011-4079

Package Information:
  https://launchpad.net/ubuntu/+source/openldap/2.4.25-1.1ubuntu4.1
  https://launchpad.net/ubuntu/+source/openldap/2.4.23-6ubuntu6.1
  https://launchpad.net/ubuntu/+source/openldap/2.4.23-0ubuntu3.7
  https://launchpad.net/ubuntu/+source/openldap/2.4.21-0ubuntu5.6