Integer truncation error in opera.dll in Opera before 11.01 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via an HTML form with a select element that contains a large number of children.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12636
http://www.vupen.com/english/advisories/2011/0231
http://www.securityfocus.com/bid/46036
http://www.opera.com/support/kb/view/982/
http://www.opera.com/docs/changelogs/windows/1101/
http://www.opera.com/docs/changelogs/unix/1101/
http://www.opera.com/docs/changelogs/mac/1101/