Bug #77428 [NEW]: mb_ereg_replace() doesn't replace a substitution variable

From: shin1x1 at gmail dot com Operating system: PHP version: 7.3.0 Package: mbstring related Bug Type: Bug Bug description:mb_ereg_replace() doesn't replace a substitution variable Description: ------------ The substitution variable of mb_ereg_replace() is not working when a substitution variable is preceded by a backslash If you look at https://3v4l.org/OjhAe the output is different for prior to PHP 7.3.0. Test script: --------------- <?php var_dump(mb_ereg_replace('(%)', '\\\1', 'a%c')); Expected result: ---------------- string(4) "a\%c" Actual result: -------------- string(5) "a\\1c" -- Edit bug report at https://bugs.php.net/bug.php?id=77428&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=77428&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=77428&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=77428&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=77428&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=77428&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=77428&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=77428&r=needscript Try newer version: https://bugs.php.net/fix.php?id=77428&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=77428&r=support Expected behavior: https://bugs.php.net/fix.php?id=77428&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=77428&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=77428&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=77428&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=77428&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=77428&r=dst IIS Stability: https://bugs.php.net/fix.php?id=77428&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=77428&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=77428&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=77428&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=77428&r=mysqlcfg