On the PHP Security Blog today, Stefan Esser has this new post with comments about the latest PHP 5.x release and the HTTP response splitting it fixes.

For all those that have not yet learned about my two new advisories through the usual channels. PHP 5.1.2 was released today, fixing among other things a serious HTTP Response Splitting vulnerability in the PHP5 session extension. The fix was implemented in a way similar to the SAPI hook in our Hardening-Patch and is the first move to get some of the Hardening-Patch features into the plain PHP. It is also merged into the PHP4 code tree.

So, basically, once the latest version of the PHP 4.x series has been released, HTTP reponse splitting issues will be a thing of the past. Great work on both sides of the version fence for taking care of this issue...