PCRE before 8.38 mishandles the (?(<digits>) and (?(R<digits>) conditions, which allows remote attackers to cause a denial of service (integer overflow) or possibly have unspecified other impact via a crafted regular expression, as demonstrated by a JavaScript RegExp object encountered by Konqueror. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-8394
