piwik -- php code execution

secunia reports:

Stefan Esser has reported a vulnerability in Piwik, which can be
exploited by malicious people to compromise a vulnerable system.
The vulnerability is caused due to the core/Cookie.php script using
“unserialize()” with user controlled input. This can be exploited to
e.g. execute arbitrary PHP code via the “__wakeup()” or “__destruct()”
methods of a serialized object passed via an HTTP cookie.