RHSA-2017:1721 - Security Advisory

Topic

An update for httpd is now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

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 proxy_util.c. With this update, bounds checking has been fixed, and httpd no longer crashes. (BZ#1463354)

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing the updated packages, the httpd daemon will be restarted automatically.

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1406822 - CVE-2016-8743 httpd: Apache HTTP Request Parsing Whitespace Defects
• BZ - 1463354 - segfault in ap_proxy_set_scoreboard_lb

CVEs

• CVE-2016-8743

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/articles/3013361