Prior to the security update released early April my system was working fine. After that, I'm getting invalid certificates everywhere:
- iTunes says "iTunes can’t verify the identity of the server “init.itunes.apple.com”." and "iTunes can’t verify the identity of the server “xp.apple.com”." when I open it.
- Chrome gives me warnings for many https sites (e.g. Google is fine, Twitter isn't).
- Most importantly I can't connect to the App Store anymore, which I was planning to do to upgrade to Yosemite given that Apple decided to not fix one of the security vulnerabilities for the previous versions.
I checked my certificates in the Keychain Access and I don't see anything wrong with them. I've also tried deleting some files related to certificate caches as I've seen mentioned somewhere else, but it didn't help either.
I'm using OS X 10.9.5 in a MacBook Air, Late 2012.
Update
This problem also applies to some systems updated from OS X 10.10 Yosemite to OS X 10.11.1 (15B42) El Capitan.