CVE-2013-3735

DISPUTED The Zend Engine in PHP before 5.4.16 RC1, and 5.5.0 before
RC2, does not properly determine whether a parser error occurred, which
allows context-dependent attackers to cause a denial of service (memory
consumption and application crash) via a crafted function definition, as
demonstrated by an attack within a shared web-hosting environment. NOTE:
the vendor’s http://php.net/security-note.php page says “for critical
security situations you should be using OS-level security by running
multiple web servers each as their own user id.”

Notes