Konqueror can associate a cookie with multiple domains when the DNS resolver has a non-root domain in its search list, which allows remote attackers to trick a user into accepting a cookie for a hostname formed via search-list expansion of the hostname entered by the user, or steal a cookie for an expanded hostname, as demonstrated by an attacker who operates an ap1.com Internet web site to steal cookies associated with an ap1.com.example.com intranet web site.

KDE Konqueror does not prevent cookies that are sent over an insecure channel (HTTP) from also being sent over a secure channel (HTTPS/SSL) in the same domain, which could allow remote attackers to steal cookies and conduct unauthorized activities, aka "Cross Security Boundary Cookie Injection."

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.