Posted by Khashayar Fereidani on Jun 20# PHP 8.5.7 mb_substr() 'SJIS-mac' size_t underflow Author: Khashayar Fereidani
Disclosure Date: 2026-06-18
Advisory: https://fereidani.com/php-857-mbsubstr-sjis-mac-sizet-underflow
Contact: https://fereidani.com/contact ## Description The mb_get_substr() function in ext/mbstring/mbstring.c
deliberately skips an early empty return guard for the SJIS-mac
encoding when from >= in_len. As a result, it falls...
mb_substr()'SJIS-mac' size_t underflow Author: Khashayar Fereidani Disclosure Date: 2026-06-18 Advisory: https://fereidani.com/php-857-mbsubstr-sjis-mac-sizet-underflow Contact: https://fereidani.com/contact ## Description Themb_get_substr()function inext/mbstring/mbstring.cdeliberately skips an early empty return guard for theSJIS-macencoding whenfrom >= in_len. As a result, it falls...