The mod_proxy module in the Apache HTTP Server 2.4.x before 2.4.10, when a reverse proxy is enabled, allows remote attackers to cause a denial of service (child-process crash) via a crafted HTTP Connection header.
https://support.apple.com/HT204659
https://bugzilla.redhat.com/show_bug.cgi?id=1120599
http://zerodayinitiative.com/advisories/ZDI-14-239/
http://www.oracle.com/technetwork/topics/security/cpujan2015-1972971.html
http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/proxy_util.c
http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/mod_proxy_http.c
http://seclists.org/fulldisclosure/2014/Jul/117
http://lists.apple.com/archives/security-announce/2015/Apr/msg00001.html