Microsoft Internet Explorer 6 on Windows XP SP2 allows remote attackers to cause a denial of service (crash) by iterating over any native function, as demonstrated with the window.alert function, which triggers a null dereference.
https://exchange.xforce.ibmcloud.com/vulnerabilities/27932
https://euvd.enisa.europa.eu/vulnerability/EUVD-2006-3909
http://www.vupen.com/english/advisories/2006/2955
http://www.securityfocus.com/bid/19140
http://browserfun.blogspot.com/2006/07/mobb-25-native-function-iterator.html