The Windows DirectWrite library, as used in Microsoft .NET Framework 3.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2, allows remote attackers to obtain sensitive information from process memory via a crafted OpenType font on a web site, aka "OpenType Font Parsing Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-044