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run code in 200+ php & hhvm versions
Bugs & Features
<?php $regex = '/((aaa)(?=xyz\Kaa))/'; $subject = "aaaaxyzaabaa"; // Comment/uncomment below as wanted. // All 3 functions are vulnerable (note, other functions are affected as well) $x=preg_replace($regex, '\0',$subject); var_dump($x);
based on 2gNdN
Output for 5.4.45, 5.5.29 - 5.5.38, 5.6.13 - 7.2.0
NULL
Output for 5.4.0 - 5.4.44, 5.5.0 - 5.5.28, 5.6.0 - 5.6.12

Process exited with code 139.