KDE Konqueror 3.5.1 and earlier allows remote attackers to cause a denial of service (application crash) by calling the replaceChild method on a DOM object, which triggers a null dereference, as demonstrated by calling document.replaceChild with a 0 (zero) argument.
Konqueror 3.1.3, 3.2.2, and possibly other versions does not properly prevent a frame in one domain from injecting content into a frame that belongs to another domain, which facilitates web site spoofing and other attacks, aka the frame injection vulnerability.