RHSA-2017:1721: Moderate: httpd security and bug fix update

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.Security Fix(es): It was discovered that the HTTP parser in httpd incorrectly allowed certain characters not permitted by the HTTP protocol specification to appear unencoded in HTTP request headers. If httpd was used in conjunction with a proxy or backend server that interpreted those characters differently, a remote attacker could possibly use this flaw to inject data into HTTP responses, resulting in proxy cache poisoning. (CVE-2016-8743) Note: The fix for the CVE-2016-8743 issue causes httpd to return "400 Bad Request" error to HTTP clients which do not strictly follow HTTP protocol specification. A newly introduced configuration directive "HttpProtocolOptions Unsafe" can be used to re-enable the old less strict parsing. However, such setting also re-introduces the CVE-2016-8743 issue.Note: Administrators of Red Hat Satellite 5 and Red Hat Satellite Proxy 5 systems should consult Red Hat Knowledgebase article 3013361 linked to in the Reference section before installing this update.Bug Fix(es): Previously, httpd was unable to correctly check a boundary of an array, and in rare cases it attempted to access an element of an array that was out of bounds. Consequently, httpd terminated unexpectedly with a segmentation fault at proxyutil.c. With this update, bounds checking has been fixed, and httpd no longer crashes. (BZ#1463354)