CVS before 1.10.8 does not properly initialize a global variable, which allows remote attackers to cause a denial of service (server crash) via the diff capability.
http://www.securityfocus.com/bid/4234
http://www.redhat.com/support/errata/RHSA-2002-026.html
http://www.iss.net/security_center/static/8366.php
http://www.debian.org/security/2002/dsa-117