Sendmail before 8.11.4, and 8.12.0 before 8.12.0.Beta10, allows local users to cause a denial of service and possibly corrupt the heap and gain privileges via race conditions in signal handlers.
http://www.securityfocus.com/bid/2794
http://www.securityfocus.com/archive/1/187127
http://www.iss.net/security_center/static/6633.php
http://rhn.redhat.com/errata/RHSA-2001-106.html
http://archives.neohapsis.com/archives/sendmail/2001-q2/0001.html