Buffer underflow in the header function in PHP 5.2.0 allows context-dependent attackers to execute arbitrary code by passing an all-whitespace string to this function, which causes it to write '\0' characters in whitespace that precedes the string.

The mb_parse_str function in PHP 4.0.0 through 4.4.6 and 5.0.0 through 5.2.1 sets the internal register_globals flag and does not disable it in certain cases when a script terminates, which allows remote attackers to invoke available PHP scripts with register_globals functionality that is not detectable by these scripts, as demonstrated by forcing a memory_limit violation.

The resource system in PHP 5.0.0 through 5.2.1 allows context-dependent attackers to execute arbitrary code by interrupting the hash_update_file function via a userspace (1) error or (2) stream handler, which can then be used to destroy and modify internal resources. NOTE: it was later reported that PHP 5.2 through 5.2.13 and 5.3 through 5.3.2 are also affected.

The resource system in PHP 4.0.0 through 4.4.6 and 5.0.0 through 5.2.1 allows context-dependent attackers to execute arbitrary code by interrupting certain functions in the GD (ext/gd) extension and unspecified other extensions via a userspace error handler, which can be used to destroy and modify internal resources.

Double free vulnerability in the session extension in PHP 5.2.0 and 5.2.1 allows context-dependent attackers to execute arbitrary code via illegal characters in a session identifier, which is rejected by an internal session storage module, which calls the session identifier generator with an improper environment, leading to code execution when the generator is interrupted, as demonstrated by triggering a memory limit violation or certain PHP errors.

ext/filter in PHP 5.2.0, when FILTER_SANITIZE_STRING is used with the FILTER_FLAG_STRIP_LOW flag, does not properly strip HTML tags, which allows remote attackers to conduct cross-site scripting (XSS) attacks via HTML with a '<' character followed by certain whitespace characters, which passes one filter but is collapsed into a valid tag, as demonstrated using %0b.

The FDF support (ext/fdf) in PHP 5.2.0 and earlier does not implement the input filtering hooks for ext/filter, which allows remote attackers to bypass web site filters via an application/vnd.fdf formatted POST.

Buffer underflow in the PHP_FILTER_TRIM_DEFAULT macro in the filtering extension (ext/filter) in PHP 5.2.0 allows context-dependent attackers to execute arbitrary code by calling filter_var with certain modes such as FILTER_VALIDATE_INT, which causes filter to write a null byte in whitespace that precedes the buffer.

The compress.bzip2:// URL wrapper provided by the bz2 extension in PHP before 4.4.7, and 5.x before 5.2.2, does not implement safemode or open_basedir checks, which allows remote attackers to read bzip2 archives located outside of the intended directories.

The zip:// URL wrapper provided by the PECL zip extension in PHP before 4.4.7, and 5.2.0 and 5.2.1, does not implement safemode or open_basedir checks, which allows remote attackers to read ZIP archives located outside of the intended directories.