The (1) S_reghop3, (2) S_reghop4, and (3) S_reghopmaybe3 functions in regexec.c in Perl before 5.24.0 allow context-dependent attackers to cause a denial of service (infinite loop) via crafted utf-8 data, as demonstrated by "a\x80."
https://usn.ubuntu.com/3625-2/
https://usn.ubuntu.com/3625-1/
https://security.gentoo.org/glsa/201701-75
https://rt.perl.org/Public/Bug/Display.html?id=123562
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05240731
https://bugzilla.redhat.com/show_bug.cgi?id=1329106
http://www.securityfocus.com/bid/86707
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.openwall.com/lists/oss-security/2016/04/20/7
http://www.openwall.com/lists/oss-security/2016/04/20/5
http://perl5.git.perl.org/perl.git/commitdiff/22b433eff9a1ffa2454e18405a56650f07b385b5
http://lists.fedoraproject.org/pipermail/package-announce/2016-May/183592.html