The MITRE CVE dictionary describes this issue as:
strtod.c, as used in the zend_strtod function in PHP 5.2 before 5.2.17 and 5.3 before 5.3.5, and other products, allows context-dependent attackers to cause a denial of service (infinite loop) via a certain floating-point value in scientific notation, which is not properly handled in x87 FPU registers, as demonstrated using 2.2250738585072011e-308.
Find out more about CVE-2010-4645 from the
MITRE CVE dictionary dictionary and
This issue leads to a temporary denial of service (high CPU consumption) when a PHP script handles numeric values from untrusted user input. It does not affect the versions of PHP as shipped with Red Hat Enterprise Linux 3, 4 or 5. It did affect the PHP 5.3 (php53) package on Red Hat Enterprise Linux 5.