Two weaknesses and some vulnerabilities have been reported in Opera, which can be exploited by malicious people to bypass certain security restrictions, disclose potentially sensitive information, and compromise a user's system.

1) An integer truncation error when processing certain specially crafted HTML pages can be exploited by e.g. tricking a user into visiting a malicious website.

2) The application allows users to perform certain actions via "opera:" URLs. This can be exploited to e.g. change certain configuration settings by tricking a user into clicking a specially crafted link via clickjacking.

3) An error when processing certain HTTP responses or redirects can be exploited to bypass certain security restrictions and e.g. disclose the content of local files by loading them as a web resource.

4) An error can cause Opera to launch the wrong executable in order to open a folder containing a downloaded file, which can lead to a malicious executable being launched.

Successful exploitation of this weakness requires significant user interaction and only affects the Windows platform.

5) The "Clear all email account passwords" option does not clear the email passwords unless the application is restarted, which can be exploited to gain access to the email accounts.

Solution
Update to version 11.01.

Provided and/or discovered by
1) Jordi Chancel
4) JVN credits Makoto Shiotsuki.
2,3,5) Reported by the vendor.

Changelog
Further details available to Secunia VIM customers

Original Advisory
Opera:
http://www.opera.com/docs/changelogs/windows/1101/
1) http://www.opera.com/support/kb/view/982/
2) http://www.opera.com/support/kb/view/983/
3) http://www.opera.com/support/kb/view/984/
4) http://www.opera.com/support/kb/view/985/
5) http://www.opera.com/support/kb/view/986/

Jordi Chancel:
https://www.alternativ-testing.fr/blog/index.php?post/2011/[CVE-XXXX-XXXX]-Opera-11-Integer-Truncation-Vulnerability

JVN:
http://jvn.jp/en/jp/JVN33880169/index.html
http://jvndb.jvn.jp/en/contents/2011/JVNDB-2011-000010.html

Deep Links
Links available to Secunia VIM customers