Published: 19 November 2012
CUPS 1.4.4, when running in certain Linux distributions such as Debian GNU/Linux, stores the web interface administrator key in /var/run/cups/certs/0 using certain permissions, which allows local users in the lpadmin group to read or write arbitrary files as root by leveraging the web interface.
On Ubuntu, file disclosure and corruption is limited by the AppArmor profile, which limits exposure. It still can access some important files though, such as /etc/shadow. Upstream patch moves dangerous configuration options to a second config file which is not web-editable. Although this is a good long-term solution, the changes are too intrusive for a security update. The most sensible thing to do at this time is to completely disable modifying the cupsd.conf file via the web interface.