Mandriva Linux Security Advisory – Raphael Marichez discovered a denial of service bug in how vixie-cron verifies crontab file integrity. A local user with the ability to create a hardlink to /etc/crontab could prevent vixie-cron from executing certain system cron jobs.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/61458/MDKSA-2007-234.txt
Source: https://packetstormsecurity.com/files/61458/Mandriva-Linux-Security-Advisory-2007.234.html