The LPRng print spooler, as shipped in CentOS Linux Advanced Server 2.1, accepts all remote print jobs by default. Updated LPRng packages are available to fix this issue.
With its default configuration, LPRng will accept job submissions from any host, which is not appropriate in a workstation environment. We are grateful to Matthew Caron for pointing out this configuration problem. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2002-0378 to this issue. The updated packages from this advisory change the job submission policy (in /etc/lpd.perms) so that jobs from remote hosts are refused by default. Those running print servers may want to adjust this policy as appropriate, for example to give access to certain hosts or subnets. For details on how to do this, see the lpd.perms(5) man page. Please note that default installations of CentOS Linux Advanced Server 2.1 include ipchains rules blocking remote access to the print spooler IP port; as a result those installations already reject remote job submissions. NOTE: There are special instructions for installing this update at the end of the "Solution" section.