"There was an error connecting to the Apple ID server" untrusted CRL issue

I started getting errors when logging into my Apple account on iTunes/App Store/iBooks etc, which I noticed today.

When attempting login, these would return the message "There was an error connecting to the Apple ID server"

Debugging this with Wireshark, I noticed that iTunes was disconnecting as soon as it saw the server SSL certificate.

I opened the domain url it was using (https://gsa.apple.com) in Safari to see whether it reported any certificate issues, and it confirmed that the intermediary certificate, though valid, couldn't be verified against it's CRL as it believes http://crl.apple.com/root.crl is an untrusted CRL.

Other OSX computers I've checked serve the same certificate, and validate the certificate successfully.

I've attempted to set the certificate to always trust, but it had no effect.

I've changed the Keychain Access -> Preferences -> Certificates -> Certificate Revocation List (CRL) to "Best attempt", which appears to fix the issue, however I'm not keen on this change as it might weaken my computer's security compared to "Require if certificate indicates"

Is there any way to restore OSX's trusted CRL list to fix this?