Oracle MySQL 5.1 before 5.1.49 and 5.0 before 5.0.92 allows remote authenticated users to cause a denial of service (mysqld daemon crash) by using EXPLAIN with crafted "SELECT ... UNION ... ORDER BY (SELECT ... WHERE ...)" statements, which triggers a NULL pointer dereference in the Item_singlerow_subselect::store function.
https://exchange.xforce.ibmcloud.com/vulnerabilities/64684
http://www.vupen.com/english/advisories/2011/0345
http://www.vupen.com/english/advisories/2011/0170
http://www.vupen.com/english/advisories/2011/0133
http://www.vupen.com/english/advisories/2011/0105
http://www.ubuntu.com/usn/USN-1397-1
http://www.ubuntu.com/usn/USN-1017-1
http://www.turbolinux.co.jp/security/2011/TLSA-2011-3j.txt
http://www.securityfocus.com/bid/42599
http://www.redhat.com/support/errata/RHSA-2011-0164.html
http://www.redhat.com/support/errata/RHSA-2010-0825.html
http://www.mandriva.com/security/advisories?name=MDVSA-2011:012
http://www.mandriva.com/security/advisories?name=MDVSA-2010:222
http://www.mandriva.com/security/advisories?name=MDVSA-2010:155
http://www.debian.org/security/2011/dsa-2143
http://support.apple.com/kb/HT4723
http://secunia.com/advisories/42936
http://secunia.com/advisories/42875
http://lists.opensuse.org/opensuse-security-announce/2010-10/msg00006.html
http://lists.apple.com/archives/security-announce/2011//Jun/msg00000.html