mod_lua.c in the mod_lua module in the Apache HTTP Server 2.3.x and 2.4.x through 2.4.10 does not support an httpd configuration in which the same Lua authorization provider is used with different arguments within different contexts, which allows remote attackers to bypass intended access restrictions in opportunistic circumstances by leveraging multiple Require directives, as demonstrated by a configuration that specifies authorization for one group to access a certain directory, and authorization for a second group to access a second directory.
https://support.apple.com/kb/HT205031
https://support.apple.com/HT205219
https://issues.apache.org/bugzilla/show_bug.cgi?id=57204
https://github.com/apache/httpd/commit/3f1693d558d0758f829c8b53993f1749ddf6ffcb
https://bugzilla.redhat.com/show_bug.cgi?id=1174077
http://www.ubuntu.com/usn/USN-2523-1
http://www.securityfocus.com/bid/73040
http://www.oracle.com/technetwork/topics/security/cpujan2016-2367955.html
http://www.openwall.com/lists/oss-security/2014/11/28/5
http://lists.fedoraproject.org/pipermail/package-announce/2015-June/159352.html