PHP is an HTML-embedded scripting language commonly used with the Apache HTTP Web server.
Multiple missing input sanitization flaws were discovered in PHP's exif extension. A specially-crafted image file could cause the PHP interpreter to crash or, possibly, disclose portions of its memory when a PHP script tried to extract Exchangeable image file format (Exif) metadata from the image file. (CVE-2009-2687, CVE-2009-3292)
A missing input sanitization flaw, leading to a buffer overflow, was discovered in PHP's gd library. A specially-crafted GD image file could cause the PHP interpreter to crash or, possibly, execute arbitrary code when opened. (CVE-2009-3546)
It was discovered that PHP did not limit the maximum number of files that can be uploaded in one request. A remote attacker could use this flaw to instigate a denial of service by causing the PHP interpreter to use lots of system resources dealing with requests containing large amounts of files to be uploaded. This vulnerability depends on file uploads being enabled (which it is, in the default PHP configuration). (CVE-2009-4017)
Note: This update introduces a new configuration option, max_file_uploads, used for limiting the number of files that can be uploaded in one request. By default, the limit is 20 files per request.
It was discovered that PHP was affected by the previously published "null prefix attack", caused by incorrect handling of NUL characters in X.509 certificates. If an attacker is able to get a carefully-crafted certificate signed by a trusted Certificate Authority, the attacker could use the certificate during a man-in-the-middle attack and potentially confuse PHP into accepting it by mistake. (CVE-2009-3291)
It was discovered that PHP's htmlspecialchars() function did not properly recognize partial multi-byte sequences for some multi-byte encodings, sending them to output without them being escaped. An attacker could use this flaw to perform a cross-site scripting attack. (CVE-2009-4142)
All php users should upgrade to these updated packages, which contain backported patches to resolve these issues. After installing the updated packages, the httpd daemon must be restarted for the update to take effect.