The Hardened-PHP project has just released another advisory about core PHP functionality, specifically in the unserialize function when dealing with arrays.

The PHP 5 branch of the PHP source code lacks the protection against possible integer overflows inside ecalloc() that is present in the PHP 4 branch and also for several years part of our Hardening-Patch and our new Suhosin-Patch.

It was discovered that such an integer overflow can be triggered when user input is passed to the unserialize() function.

You can get the full details from this advisory release including a recommendation to patch the installation until it is corrected in the current distribution.