Opera before 11.65 does not ensure that keyboard sequences are associated with a visible window, which makes it easier for user-assisted remote attackers to conduct cross-site scripting (XSS) attacks or execute arbitrary code via a crafted web site, related to a "hidden keyboard navigation" issue.

Opera before 9.63 does not properly verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.

Opera before 11.62 on UNIX, when used in conjunction with an unspecified printing application, allows local users to overwrite arbitrary files via a symlink attack on a temporary file during printing.

Opera before 11.62 on UNIX uses world-readable permissions for temporary files during printing, which allows local users to obtain sensitive information by reading these files.

Opera before 11.62 on Mac OS X allows remote attackers to spoof the address field and security dialogs via crafted styling that causes page content to be displayed outside of the intended content area.

Opera before 11.62 allows remote attackers to spoof the address field by triggering a page reload followed by a redirect to a different domain.

Opera before 11.62 allows remote attackers to spoof the address field by triggering the launch of a dialog window associated with a different domain.

Opera before 11.62 allows remote attackers to bypass the Same Origin Policy via the (1) history.pushState and (2) history.replaceState functions in conjunction with cross-domain frames, leading to unintended read access to history.state information.

Opera before 11.62 does not ensure that a dialog window is placed on top of content windows, which makes it easier for user-assisted remote attackers to trick users into downloading and executing arbitrary files via a download dialog located under other windows.

Opera before 11.62 allows user-assisted remote attackers to trick users into downloading and executing arbitrary files via a small window for the download dialog.

Multiple integer overflows in Opera 11.60 and earlier allow remote attackers to cause a denial of service (application crash) via a large integer argument to the (1) Int32Array, (2) Float32Array, (3) Float64Array, (4) Uint32Array, (5) Int16Array, or (6) ArrayBuffer function. NOTE: the vendor reportedly characterizes this as "a stability issue, not a security issue."

Opera 11.60 and earlier does not prevent capture of data about the times of Same Origin Policy violations during IFRAME loading attempts, which makes it easier for remote attackers to determine whether a document exists in the browser cache via crafted JavaScript code.

Opera before 11.51 allows remote attackers to cause an insecure site to appear secure or trusted via unspecified actions related to Extended Validation and loading content from trusted sources in an unspecified sequence that causes the address field and page information dialog to contain security information based on the trusted site, instead of the insecure site.

Opera cannot properly restrict modifications to cookies established in HTTPS sessions, which allows man-in-the-middle attackers to overwrite or delete arbitrary cookies via a Set-Cookie header in an HTTP response, related to lack of the HTTP Strict Transport Security (HSTS) includeSubDomains feature, aka a "cookie forcing" issue.

Unspecified vulnerability in Opera before 11.11 allows remote attackers to cause a denial of service (application crash) via vectors involving a Certificate Revocation List (CRL) file, as demonstrated by the multicert-ca-02.crl file.

Opera before 11.11 does not properly handle destruction of a Silverlight instance, which allows remote attackers to cause a denial of service (application crash) via a web page, as demonstrated by vod.onet.pl.

The Cascading Style Sheets (CSS) implementation in Opera before 11.11 does not properly handle the column-count property, which allows remote attackers to cause a denial of service (infinite repaint loop and application hang) via a web page, as demonstrated by an unspecified Wikipedia page.

Opera before 11.11 allows user-assisted remote attackers to cause a denial of service (application crash) via a crafted web page that is not properly handled during a reload occurring after the opening of a popup of the Easy Sticky Note extension.

Unspecified vulnerability in Opera before 11.11 allows remote attackers to cause a denial of service (application crash) via unknown content on a web page, as demonstrated by www.falk.de.

Opera before 11.11 does not properly implement FRAMESET elements, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via vectors related to page unload.