Microsoft Silverlight 5 before 5.1.20513.0 does not properly initialize arrays, which allows remote attackers to execute arbitrary code or cause a denial of service (NULL pointer dereference) via a crafted Silverlight application, aka "Null Pointer Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A17389
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16892
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-052