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.

Konqueror in KDE 3.1.3 and earlier (kdelibs) allows remote attackers to bypass intended cookie access restrictions on a web application via "%2e%2e" (encoded dot dot) directory traversal sequences in a URL, which causes Konqueror to send the cookie outside the specified URL subsets, e.g. to a vulnerable application that runs on the same server as the target application.

KDE Konqueror for KDE 3.1.2 and earlier does not remove authentication credentials from URLs of the "user:password@host" form in the HTTP-Referer header, which could allow remote web sites to steal the credentials for pages that link to the sites.

Konqueror Embedded and KDE 2.2.2 and earlier does not validate the Common Name (CN) field for X.509 Certificates, which could allow remote attackers to spoof certificates via a man-in-the-middle attack.