Opera before 10.53 on Windows and Mac OS X does not properly handle a series of document modifications that occur asynchronously, which allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via JavaScript that writes <marquee> sequences in an infinite loop, leading to attempted use of uninitialized memory. NOTE: this might overlap CVE-2006-6955.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11927
https://exchange.xforce.ibmcloud.com/vulnerabilities/58231
http://www.vupen.com/english/advisories/2010/0999
http://www.opera.com/support/kb/view/953/
http://www.opera.com/docs/changelogs/windows/1053/
http://www.opera.com/docs/changelogs/mac/1053/
http://secunia.com/advisories/39590
http://my.opera.com/desktopteam/blog/2010/04/28/opera-10-53-rc1-for-windows-and-mac