Michael Calmer and Marcus Meissner discovered that several krb5 tools did not check the return values from setuid() system calls. On systems that have configured user process limits, it may be possible for an attacker to cause setuid() to fail via resource starvation. In that situation, the tools will not reduce their privilege levels, and will continue operation as the root user.
By default, Ubuntu does not ship with user process limits.
Please note that these packages are not officially supported by Ubuntu (they are in the ‘universe’ component of the archive).