Microsoft .NET Framework 2.0, 3.5, 3.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2 and 4.7 allow an attacker to bypass Enhanced Security Usage taggings when they present a certificate that is invalid for a specific use, aka ".NET Security Feature Bypass Vulnerability."
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-0248