We aren't quite sure when the problem will be fixed but it is affecting all the current Oculus Rift users.
For now, if you are an Oculus Rift owner, it would be best to keep an eye out for a software update, or an official announcement from Oculus VR themselves. It was first flagged on the Oculus forums, and some quick digging uncovered the fact that a certificate for the Oculus Runtime Service expired earlier today, which is a pretty big oversight on Oculus's part. This issue is a bummer to gamers that aren't going to get to play the titles they've purchased until the issue is resolved, but it's a much less forgivable issue for commercial users who use the headset. It was a particular problem for developer Adam Boyne (via Polygon), whose virtual reality demo was foiled by the error.
Follow the issue at the Oculus Forums here.More news: FDA Approves Direct-to-Consumer Cancer Mutation Test
That's quite the oversight, but thus far, Oculus hasn't confirmed that this expired security certificate is at the core of the problem. "Our teams apologize for any inconvenience this may be causing you and appreciate your patience while we work on a resolution". The only way to fix this is for Oculus to release an updated version of OculusAppFramework.dll with a new certificate.
For now, there's no timeline on a fix, but Oculus says it will update that support thread as it learns more. Thankfully, there appears to be a workaround at present - by disabling the Automatically set System date and time option inside Windows, then changing your PC's date to a week or so ago, when the certificate was still valid.