crontab in Vixie cron 3.0.1 and earlier does not properly drop privileges after the failed parsing of a modification operation, which could allow a local attacker to gain additional privileges when an editor is called to correct the error.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6508
http://www.novell.com/linux/security/advisories/2001_017_cron_txt.html
http://www.linux-mandrake.com/en/security/2001/MDKSA-2001-050.php3