Microsoft Internet Explorer 5.22, and other 5 through 6 SP1 versions, sends Referer headers containing https:// URLs in requests for http:// URLs, which allows remote attackers to obtain potentially sensitive information by reading Referer log data.

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 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.