Microsoft Internet Explorer 6 on Windows XP SP2 allows remote attackers to cause a denial of service (crash) by creating an object inside an iframe, deleting the frame by setting its location.href to about:blank, then accessing a property of the object within the deleted frame, which triggers a NULL pointer dereference. NOTE: it was later reported that 7.0.6000.16473 and earlier are also affected.
https://exchange.xforce.ibmcloud.com/vulnerabilities/28068