Multiple buffer overflows in libtidy, as used in the Tidy extension for PHP 5.2.3 and possibly other products, allow context-dependent attackers to execute arbitrary code via (1) a long second argument to the tidy_parse_string function or (2) an unspecified vector to the tidy_repair_string function.  NOTE: this might only be an issue in environments where vsnprintf is implemented as a wrapper for vsprintf.