A denial of service vulnerability exists when .NET Framework fails to properly handle certain Extensible Stylesheet Language Transformations (XSLT). An attacker who successfully exploited this vulnerability could cause server performance to degrade significantly enough to cause a denial of service condition.
To exploit the vulnerability, an attacker could insert specially crafted XSLT into a client-side XML web part, causing the server to recursively compile XSLT transforms. This could cause a denial of service attack and disrupted server availability. The security update addresses the vulnerability by correcting how .NET Framework handles XSLT.

Further information on this exploit is available at : MS16-019