Internet Explorer 5 does not modify the security zone for a document that is being loaded into a window until after the document has been loaded, which could allow remote attackers to execute Javascript in a different security context while the document is loading.
Internet Explorer 5.0 and 5.01 allows remote attackers to modify or execute files via the Import/Export Favorites feature, aka the "ImportExportFavorites" vulnerability.
Internet Explorer 5.01 through 6 SP1 allows remote attackers to direct drag and drop behaviors and other mouse click actions to other windows by using method caching (SaveRef) to access the window.moveBy method, which is otherwise inaccessible, as demonstrated by HijackClickV2, a different vulnerability than CVE-2003-0823, aka the "Function Pointer Drag and Drop Vulnerability."
Internet Explorer 5.01 through 6 SP1 allows remote attackers to bypass zone restrictions via a javascript protocol URL in a sub-frame, which is added to the history list and executed in the top window's zone when the history.back (back) function is called, as demonstrated by BackToFramedJpu, aka the "Travel Log Cross Domain Vulnerability."