The compile_branch function in pcre_compile.c in PCRE 8.x before 8.39 and pcre2_compile.c in PCRE2 before 10.22 mishandles patterns containing an (*ACCEPT) substring in conjunction with nested parentheses, which allows remote attackers to execute arbitrary code or cause a denial of service (stack-based buffer overflow) via a crafted regular expression, as demonstrated by a JavaScript RegExp object encountered by Konqueror, aka ZDI-CAN-3542.
https://www.tenable.com/security/tns-2016-18
https://bugzilla.redhat.com/show_bug.cgi?id=1311503
https://bugs.debian.org/815921
https://bugs.debian.org/815920
https://bto.bluecoat.com/security-advisory/sa128
https://access.redhat.com/errata/RHSA-2016:1132
http://www.securityfocus.com/bid/84810
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www-01.ibm.com/support/docview.wss?uid=isg3T1023886
http://vcs.pcre.org/pcre?view=revision&revision=1631