The sapi_header_op function in main/SAPI.c in PHP before 5.4.38, 5.5.x before 5.5.22, and 5.6.x before 5.6.6 supports deprecated line folding without considering browser compatibility, which allows remote attackers to conduct cross-site scripting (XSS) attacks against Internet Explorer by leveraging (1) %0A%20 or (2) %0D%0A%20 mishandling in the header function.
https://github.com/php/php-src/commit/996faf964bba1aec06b153b370a7f20d3dd2bb8b?w=1
https://bugs.php.net/bug.php?id=68978
http://www.openwall.com/lists/oss-security/2016/06/20/3
http://rhn.redhat.com/errata/RHSA-2016-2750.html
http://lists.opensuse.org/opensuse-updates/2016-08/msg00003.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00004.html