cups: "/usr/bin/lp: Not allowed to print."

Since yesterday I am not allowed to print anymore, even as root. I am not allowed to change settings as root in the web interface dialog. It doesn't ask for credentials

rpm -q cups
cups-1.5.4-5.2.1.i586

I suppose the issue has been pulled in by an automatic security update, as I didn't change anything and printing worked fine
until yesterday evening.

Any suggestions what to try would be appreciated.