DotDeb.org has released PHP 4.3.8 packages for Debian GNU/Linux 3.0
PHP 4.3.8 has just been published, fixing two important security holes. You'll find the details on the PHP4 Changelog.Here the apt source for /etc/apt/sources.list:
Then the dotdeb packages have been updated. Just apt-get update/upgrade to update your PHP4 to the 4.3.8 release.
deb http://packages.dotdeb.org ./