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.