Opera before 10.01 does not properly restrict HTML in a (1) RSS or (2) Atom feed, which allows remote attackers to conduct cross-site scripting (XSS) attacks, and conduct cross-zone scripting attacks involving the Feed Subscription Page to read feeds or create feed subscriptions, via a crafted feed, related to the rendering of the application/rss+xml content type as "scripted content."

Opera 9.52 and earlier allows remote attackers to cause a denial of service (CPU consumption) via a series of automatic submissions of a form containing a KEYGEN element, a related issue to CVE-2009-1828.

Opera before 10.00 does not check all intermediate X.509 certificates for revocation, which makes it easier for remote SSL servers to bypass validation of the certificate chain via a revoked certificate.

Opera before 10.00 trusts root X.509 certificates signed with the MD2 algorithm, which makes it easier for man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted server certificate.

Opera before 10.00 does not properly handle a (1) '\0' character or (2) invalid wildcard character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority.

Opera before 10.00 does not properly display all characters in Internationalized Domain Names (IDN) in the address bar, which allows remote attackers to spoof URLs and conduct phishing attacks, related to Unicode and Punycode.

Opera before 10.00 on Linux, Solaris, and FreeBSD does not properly implement the "INPUT TYPE=file" functionality, which allows remote attackers to trick a user into uploading an unintended file via vectors involving a "dropped file."

Opera before 10.00, when a collapsed address bar is used, does not properly update the domain name from the previously visited site to the currently visited site, which might allow remote attackers to spoof URLs.

Opera 9.52 and earlier, and 10.00 Beta 3 Build 1699, does not properly block data: URIs in Location headers in HTTP responses, which allows remote attackers to conduct cross-site scripting (XSS) attacks via vectors related to (1) injecting a Location header that contains JavaScript sequences in a data:text/html URI or (2) entering a data:text/html URI with JavaScript sequences when specifying the content of a Location header. NOTE: the JavaScript executes outside of the context of the HTTP site.

Opera 9.52 and earlier allows remote attackers to cause a denial of service (CPU and memory consumption, and application hang) via a long Unicode string argument to the write method, a related issue to CVE-2009-2479.