There’s a vulnerability in the Kerberos implementation in several versions of Ubuntu, which could allow an attacker to cause a denial-of-service on vulnerable servers. The bug is in Ubuntu 8.04, Ubuntu 9.10, Ubuntu 10.04 and Ubuntu 10.10.
The bug is in the Ubuntu implementation of the Kerberos authentication protocol. Ubuntu has released a slew of new packages to fix the flaw. The group said that in most cases, a normal system update will add the new fixes.
From the Ubuntu advisory:
Keiichi Mori discovered that the MIT krb5 KDC database propagation
daemon (kpropd) is vulnerable to a denial of service attack due
to improper logic when a worker child process exited because
of invalid network input. This could only occur when kpropd is
running in standalone mode; kpropd was not affected when running in
incremental propagation mode (“iprop”) or as an inetd server. This
issue only affects Ubuntu 9.10, Ubuntu 10.04 LTS, and Ubuntu
Kevin Longfellow and others discovered that the MIT krb5 Key
Distribution Center (KDC) daemon is vulnerable to denial of service
attacks when using an LDAP back end due to improper handling of
network input. (CVE-2011-0281, CVE-2011-0282)
Kerberos is a key authentication protocol that’s used in a huge number of open-source and commercial products.