PHP 4.0.0 through 4.4.6 and 5.0.0 through 5.2.1 allows context-dependent attackers to read arbitrary memory locations via an interruption that triggers a user space error handler that changes a parameter to an arbitrary pointer, as demonstrated via the iptcembed function, which calls certain convert_to_* functions with its input parameters.
https://exchange.xforce.ibmcloud.com/vulnerabilities/33750
http://www.gentoo.org/security/en/glsa/glsa-200710-02.xml