Two vulnerabilities in the Massachusetts Institute of Technology (MIT) Kerberos 5 implementation that affect Cisco VPN 3000 Series Concentrators have been announced by the MIT Kerberos Team. Cisco VPN 3000 Series Concentrators authenticating users against a Kerberos Key Distribution Center (KDC) may be vulnerable to remote code execution and to Denial of Service (DoS) attacks. Cisco has made free software available to address these problems. Cisco VPN 3000 Series Concentrators not authenticating users against a Kerberos Key Distribution Center (KDC) are not impacted. No exploitations of these vulnerabilities have been reported. This advisory is available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040831-krb5.