PCRE 7.8 and 8.32 through 8.37, and PCRE2 10.10 mishandle group empty matches, which might allow remote attackers to cause a denial of service (stack-based buffer overflow) via a crafted regular expression, as demonstrated by /^(?:(?(1)\\.|([^\\\\W_])?)+)+$/.
http://rhn.redhat.com/errata/RHSA-2016-1025.html
http://rhn.redhat.com/errata/RHSA-2016-2750.html
http://vcs.pcre.org/pcre?view=revision&revision=1566
http://www.openwall.com/lists/oss-security/2015/06/03/7
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www.securityfocus.com/bid/75018
http://www-01.ibm.com/support/docview.wss?uid=isg3T1023886
https://access.redhat.com/errata/RHSA-2016:1132
Source: MITRE
Published: 2016-12-13
Updated: 2018-05-18
Type: CWE-119
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH