Opera is a multi-platform web browser.
SEC Consult has discovered a buffer overflow in the code processing style sheet attributes. It is caused by an integer signedness error in a length check followed by a call to a string function. It seems to be hard to exploit this buffer overflow to execute arbitrary code because of the very large amount memory that has to be copied.
A remote attacker can entice a user to visit a web page containing a specially crafted style sheet attribute that will crash the user's browser and maybe lead to the execution of arbitrary code.
There is no known workaround at this time.
All Opera users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-client/opera-8.54"