Google Chrome detects http content in https web pages only when the top-level frame uses https, which allows man-in-the-middle attackers to execute arbitrary web script, in an https site's context, by modifying an http page to include an https iframe that references a script file on an http site, related to "HTTP-Intended-but-HTTPS-Loadable (HPIHSL) pages."

The HTML parsing engine in Opera before 9.63 allows remote attackers to execute arbitrary code via crafted web pages that trigger an invalid pointer calculation and heap corruption.

Opera 9.51 on Windows XP does not properly handle (1) multipart/mixed e-mail messages with many MIME parts and possibly (2) e-mail messages with many "Content-type: message/rfc822;" headers, which allows remote attackers to cause a denial of service (stack consumption or other resource consumption) via a large e-mail message, a related issue to CVE-2006-1173.

Opera, probably before 7.50, 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.