According to security firm Secunia, the bug affect all Opera versions prior to 9.52. Users who chose not to update should expect to become the victims of cross-site scripting attacks, theft of sensitive information, or even the infestation of the entire system.

The full list is down below:

– An unspecified error exists when Opera is executed as a protocol handler. This can be exploited to cause a crash and potentially execute arbitrary code. It only affects Opera for Windows.
– The problem is that a web page can change the address of frames from other sites opened inside a pop-up window. This can be exploited to load malicious content into a frame of a trusted website.
– An unspecified error can be exploited to conduct cross-site scripting attacks. No further information is currently available.
– An error exists in the processing of custom shortcut and menu commands. This can be exploited to execute applications with potentially dangerous parameters, created from uninitialized memory. Successful exploitation may allow execution of arbitrary code, but requires that a user is tricked into modifying shortcuts or menu files.
– An error exists while reporting websites as secure for browsing. This can be exploited to determine the reporting of an insecure website as secure by including a frame with content from a secure website.
– An error exists when checking if a web page links to a local file. This can be exploited to link to local feed source files and potentially determine if a file is present on the local system.
– An error exists when processing news feed subscription requests. This can be exploited to change the address field to the address of the malicious web page and mislead a user.

Opera 9.52 is available here for download.