Kerberos is a networked authentication system which uses a trusted third party (a KDC) to authenticate clients and servers to each other.
The krb5-workstation package includes a Kerberos-aware telnet client. Two buffer overflow flaws were discovered in the way the telnet client handles messages from a server. An attacker may be able to execute arbitrary code on a victim's machine if the victim can be tricked into connecting to a malicious telnet server. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the names CAN-2005-0468 and CAN-2005-0469 to these issues.
Users of krb5 should update to these erratum packages which contain a backported patch to correct this issue.
Red Hat would like to thank iDEFENSE for their responsible disclosure of this issue.