Microsoft .NET Framework is prone to a security-bypass vulnerability because it fails to properly validate certain elements of a signed XML document. An attacker can exploit this issue to bypass certain security restrictions and perform unauthorized actions. This may aid in further attacks.
Block external access at the network boundary, unless external parties require service.
If global access isn't needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of exploits.
Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.
Communicate sensitive information through secure means.
Use multiple layers of encryption when communicating sensitive information between a client and a server. This will reduce the chance of a successful exploit.
Updates are available. Please see the references or vendor advisory for more information.