Integer overflow in PHP 5 up to 5.1.6 and 4 before 4.3.0 allows remote attackers to execute arbitrary code via an argument to the unserialize PHP function with a large value for the number of array elements, which triggers the overflow in the Zend Engine ecalloc function (Zend/zend_alloc.c).

Race condition in the symlink function in PHP 5.1.6 and earlier allows local users to bypass the open_basedir restriction by using a combination of symlink, mkdir, and unlink functions to change the file path after the open_basedir check and before the file is opened by the underlying system, as demonstrated by symlinking a symlink into a subdirectory, to point to a parent directory via .. (dot dot) sequences, and then unlinking the resulting symlink.

PHP 4.x up to 4.4.4 and PHP 5 up to 5.1.6 allows local users to bypass certain Apache HTTP Server httpd.conf options, such as safe_mode and open_basedir, via the ini_restore function, which resets the values to their php.ini (Master Value) defaults.

PHP before 4.4.3 and 5.x before 5.1.4 does not limit the character set of the session identifier (PHPSESSID) for third party session handlers, which might make it easier for remote attackers to exploit other vulnerabilities by inserting PHP code into the PHPSESSID, which is stored in the session file. NOTE: it could be argued that this not a vulnerability in PHP itself, rather a design limitation that enables certain attacks against session handlers that do not account for this limitation.

scanf.c in PHP 5.1.4 and earlier, and 4.4.3 and earlier, allows context-dependent attackers to execute arbitrary code via a sscanf PHP function call that performs argument swapping, which increments an index past the end of an array and triggers a buffer over-read.

The error_log function in basic_functions.c in PHP before 4.4.4 and 5.x before 5.1.5 allows local users to bypass safe mode and open_basedir restrictions via a "php://" or other scheme in the third argument, which disables safe mode.

zend_hash_del_key_or_index in zend_hash.c in PHP before 4.4.3 and 5.x before 5.1.3 can cause zend_hash_del to delete the wrong element, which prevents a variable from being unset even when the PHP unset function is called, which might cause the variable's value to be used in security-relevant operations.

Buffer consumption vulnerability in the tempnam function in PHP 5.1.4 and 4.x before 4.4.3 allows local users to bypass restrictions and create PHP files with fixed names in other directories via a pathname argument longer than MAXPATHLEN, which prevents a unique string from being appended to the filename.

The copy function in file.c in PHP 4.4.2 and 5.1.2 allows local users to bypass safe mode and read arbitrary files via a source argument containing a compress.zlib:// URI.

Directory traversal vulnerability in file.c in PHP 4.4.2 and 5.1.2 allows local users to bypass open_basedir restrictions allows remote attackers to create files in arbitrary directories via the tempnam function.