The /proc filesystem in Linux allows local users to obtain sensitive information by opening various entries in /proc/self before executing a setuid program, which causes the program to fail to change the ownership and permissions of those entries.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A328
http://www.redhat.com/support/errata/RHSA-2003-239.html
http://www.redhat.com/support/errata/RHSA-2003-238.html
http://www.redhat.com/support/errata/RHSA-2003-198.html
http://www.debian.org/security/2004/dsa-423