Users can't login after mysql update

We have a few installations and on all only super admins can now login.

This has occurred after our servers have been updated to prevent the recent mysql exploitation http://www.theregister.co.uk/2016/09/13/mysql_security_bug/

The CPs and the databases show the users listed but when they try to login they get the following message: <<! Invalid username or password.>>

Users who have access vis safe cracker / Channel Forms are unaffected.

Any ideas?