PHP is an HTML-embedded scripting language commonly used with the Apache HTTP Server.
A flaw was found in the way PHP parsed multipart HTTP POST requests. A specially crafted request could cause PHP to use an excessive amount of CPU time. (CVE-2015-4024)
An integer overflow flaw leading to a heap-based buffer overflow was found in the way PHP's FTP extension parsed file listing FTP server responses. A malicious FTP server could use this flaw to cause a PHP application to crash or, possibly, execute arbitrary code. (CVE-2015-4022)
It was found that certain PHP functions did not properly handle file names containing 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. (CVE-2015-4025, CVE-2015-4026, CVE-2015-4598)
An integer underflow flaw leading to out-of-bounds memory access was found in the way PHP's Phar extension parsed Phar archives. A specially crafted archive could cause PHP to crash or, possibly, execute arbitrary code when opened. (CVE-2015-4021)
All php54-php users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the httpd service must be restarted for the update to take effect.