Opera is a multi-platform web browser.
An error known as "a virtual function call on an invalid pointer" has been discovered in the JavaScript engine (CVE-2007-4367). Furthermore, iDefense Labs reported that an already-freed pointer may be still used under unspecified circumstances in the BitTorrent support (CVE-2007-3929). At last, minor other errors have been discovered, relative to memory read protection (Opera Advisory 861) and URI displays (CVE-2007-3142, CVE-2007-3819).
A remote attacker could trigger the BitTorrent vulnerability by enticing a user into starting a malicious BitTorrent download, and execute arbitrary code through unspecified vectors. Additionally, a specially crafted JavaScript may trigger the "virtual function" vulnerability. The JavaScript engine can also access previously freed but uncleaned memory. Finally, a user can be fooled with a too long HTTP server name that does not fit the dialog box, or a URI containing whitespaces.
There is no known workaround at this time for all these vulnerabilities.
All Opera users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-client/opera-9.23"