inc/functions_time.php in MyBB (aka MyBulletinBoard) 1.4.10, and possibly earlier versions, allows remote attackers to cause a denial of service (CPU consumption) via a crafted request with a large year value, which triggers a long loop, as reachable through member.php and possibly other vectors.
blog.mybboard.net/2009/12/29/mybb-1-4-11-released-minor-patch-security-update/
dev.mybboard.net/issues/600
dev.mybboard.net/projects/mybb/repository/revisions/4613/diff/branches/1.4-stable/inc/functions_time.php
openwall.com/lists/oss-security/2010/10/08/7
openwall.com/lists/oss-security/2010/10/11/8
openwall.com/lists/oss-security/2010/12/06/2
secunia.com/advisories/37906