BIT-LIBPHP-2020-7060 global buffer-overflow in mbfl_filt_conv_big5_wchar

When using certain mbstring functions to convert multibyte encodings, in PHP versions 7.2.x below 7.2.27, 7.3.x below 7.3.14 and 7.4.x below 7.4.2 it is possible to supply data that will cause function mbflfiltconvbig5wchar to read past the allocated buffer. This may lead to information disclosur...