brent This emergency release only address this expired certificate issue (tip: use the changelog tab in the software center to see the details about the update).
The previous things weren't fixes but workarounds, some consiting of decreasing the security by not checking the signature anymore).
It's not just the certificate of an extension that was expired but an intermediate CA between the (root) certificate authority and the extensions certificates -> anything that depends on this intermediate CA was invalidated.
A new intermediate CA certificate had to be issued, then all the extensions had to be signed with a new certificate and had to be enabled back.