If you are an Intel Haswell 4th Gen Core CPU owner and use the built-in Intel HD-based integrated graphics processor (IGP) to play DirectX 12 games, there's bad news for you. The company announced last month that it has disabled the DirectX 12 capabilities of these processors in order to mitigate a security vulnerability that it has identified.
A potential security vulnerability in Intel® Graphics may allow escalation of privilege on 4th Generation Intel® Core™ processors. Intel has released a software update to mitigate this potential vulnerability. In order to mitigate the vulnerability, DirectX 12 capabilities were deprecated.
As such, the following processor lineups have lost their DirectX 12 feature-set since the driver version 220.127.116.1107:
4th Generation Intel® Core™ Processors with Intel® Iris™ Pro Graphics 5200
4th Generation Intel® Core™ Processors with Intel® Iris™ Graphics 5100
4th Generation Intel® Core™ Processors with Intel® HD Graphics 5000/4600/4400/4200
Intel® Pentium® and Celeron® Processors with Intel® HD Graphics based on 4th Generation Intel® Core™
Sadly, Intel hasn't gone into detail about what exactly the discovered security vulnerability is or how exactly it functions nor its relationship with DirectX 12. The company has added however that users can still apply the previous driver version 18.104.22.16863 or older to re-enable DirectX 12 on these CPUs. Of course, you'd still need Windows 10 to run it since DirectX 12 isn't supported on anything older.