There is a vulnerability posted in June under CVE-2010-2225 regarding a bug in the PHP SplObjectStorage. I found an excellent analysis made for this vulnerability, including a POC. More information at http://nibbles.tuxfamily.org/?p=1837#more-1837.

If you use PHP and a vulnerable version, find the patch at http://svn.php.net/viewvc?view=revision&revision=300843.

-- Manuel Humberto Santander Peláez | http://twitter.com/manuelsantander | http://manuel.santander.name | msantand at isc dot sans dot org