regex.c in GNU ed before 1.14.1 allows attackers to cause a denial of service (crash) via a malformed command, which triggers an invalid free.
https://lists.gnu.org/archive/html/bug-ed/2017-01/msg00000.html
http://www.securityfocus.com/bid/95422
http://www.openwall.com/lists/oss-security/2017/01/13/3
http://www.openwall.com/lists/oss-security/2017/01/12/7