Microsoft .NET Framework 2.0 SP2, 3.5, 3.5 SP1, 3.5.1, 4, and 4.5 does not properly parse a DTD during XML digital-signature validation, which allows remote attackers to cause a denial of service (application crash or hang) via a crafted signed XML document, aka "Entity Expansion Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18517
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-082