PHP is an HTML-embedded scripting language commonly used with the Apache HTTP Server. It was found that PHP did not properly handle file names with a NULL character. A remote attacker could possibly use this flaw to make a PHP script access unexpected files and bypass intended file system access restrictions. It was found that PHP did not check for carriage returns in HTTP headers, allowing intended HTTP response splitting protections to be bypassed. Depending on the web browser the victim is using, a remote attacker could use this flaw to perform HTTP response splitting attacks. A flaw was found in PHP"s SSL client"s hostname identity check when handling certificates that contain hostnames with NULL bytes. If an attacker was able to get a carefully crafted certificate signed by a trusted Certificate Authority, the attacker could use the certificate to conduct man-in-the-middle attacks to spoof SSL servers. An integer signedness issue, leading to a heap-based buffer underflow, was found in the PHP scandir function. If a remote attacker could upload an excessively large number of files to a directory the scandir function runs on, it could cause the PHP interpreter to crash or, possibly, execute arbitrary code. It was found that PHP did not correctly handle the magic_quotes_gpc configuration directive. This could result in magic_quotes_gpc input escaping not being applied in all cases, possibly making it easier for a remote attacker to perform SQL injection attacks. It was found that the PHP SOAP parser allowed the expansion of external XML entities during SOAP message parsing. A remote attacker could possibly use this flaw to read arbitrary files that are accessible to a PHP application using a SOAP extension. These updated php53 packages also include numerous bug fixes and enhancements. Space precludes documenting all of these changes in this advisory. Users are directed to the Red Hat Enterprise Linux 5.10 Technical Notes, linked to in the References, for information on the most significant of these changes. All PHP users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement. After installing the updated packages, the httpd daemon must be restarted for the update to take effect.