Microsoft Internet Explorer 5 SP4 and 6 do not properly garbage collect when "multiple imports are used on a styleSheets collection" to construct a chain of Cascading Style Sheets (CSS), which allows remote attackers to execute arbitrary code via unspecified vectors.

Microsoft Internet Explorer before 8 displays a cached certificate for a (1) 4xx or (2) 5xx CONNECT response page returned by a proxy server, which allows man-in-the-middle attackers to spoof an arbitrary https site by letting a browser obtain a valid certificate from this site during one request, and then sending the browser a crafted 502 response page upon a subsequent request.

Microsoft Internet Explorer before 8 uses the HTTP Host header to determine the context of a document provided in a (1) 4xx or (2) 5xx CONNECT response from a proxy server, which allows man-in-the-middle attackers to execute arbitrary web script by modifying this CONNECT response, aka an "SSL tampering" attack.

Microsoft Internet Explorer 4.0 through 7 allows remote attackers to determine the existence of local files that have associated images via a res:// URI in the src property of a JavaScript Image object, as demonstrated by the URI for a bitmap image resource within a (1) .exe or (2) .dll file.