Kerberos in Microsoft Windows Server 2008 R2 and Windows 7 does not prevent a session from changing from strong encryption to DES encryption, which allows man-in-the-middle attackers to spoof network traffic and obtain sensitive information via a DES downgrade, aka “Kerberos Spoofing Vulnerability.”
osvdb.org/70835
secunia.com/advisories/43257
support.avaya.com/css/P8/documents/100127250
www.securityfocus.com/bid/46140
www.securitytracker.com/id?1025048
www.vupen.com/english/advisories/2011/0326
docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-013
exchange.xforce.ibmcloud.com/vulnerabilities/64901
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12498