Integer overflow in the mt_rand function in PHP before 5.3.4 might make it easier for context-dependent attackers to predict the return values by leveraging a script's use of a large max parameter, as demonstrated by a value that exceeds mt_getrandmax.
PHP before 5.3.4 accepts the \0 character in a pathname, which might allow context-dependent attackers to bypass intended access restrictions by placing a safe file extension after this character, as demonstrated by .php\0.jpg at the end of the argument to the file_exists function.
The iconv_mime_decode_headers function in the Iconv extension in PHP before 5.3.4 does not properly handle encodings that are unrecognized by the iconv and mbstring (aka Multibyte String) implementations, which allows remote attackers to trigger an incomplete output array, and possibly bypass spam detection or have unspecified other impact, via a crafted Subject header in an e-mail message, as demonstrated by the ks_c_5601-1987 character set.
strtod.c, as used in the zend_strtod function in PHP 5.2 before 5.2.17 and 5.3 before 5.3.5, and other products, allows context-dependent attackers to cause a denial of service (infinite loop) via a certain floating-point value in scientific notation, which is not properly handled in x87 FPU registers, as demonstrated using 2.2250738585072011e-308.
Integer overflow in the NumberFormatter::getSymbol (aka numfmt_get_symbol) function in PHP 5.3.3 and earlier allows context-dependent attackers to cause a denial of service (application crash) via an invalid argument.
The unserialize function in PHP 5.3.0 and earlier allows context-dependent attackers to cause a denial of service (resource consumption) via a deeply nested serialized variable, as demonstrated by a string beginning with a:1: followed by many {a:1: sequences.
The parse_str function in (1) PHP, (2) Hardened-PHP, and (3) Suhosin, when called without a second parameter, might allow remote attackers to overwrite arbitrary variables by specifying variable names and values in the string to be parsed. NOTE: it is not clear whether this is a design limitation of the function or a bug in PHP, although it is likely to be regarded as a bug in Hardened-PHP and Suhosin.