RHSA-2016:1138 - Security Advisory

Topic

An update for squid 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

Squid is a high-performance proxy caching server for web clients, supporting FTP, Gopher, and HTTP data objects.

Security Fix(es):

• A buffer overflow flaw was found in the way the Squid cachemgr.cgi utility processed remotely relayed Squid input. When the CGI interface utility is used, a remote attacker could possibly use this flaw to execute arbitrary code. (CVE-2016-4051)
• Buffer overflow and input validation flaws were found in the way Squid processed ESI responses. If Squid was used as a reverse proxy, or for TLS/HTTPS interception, a remote attacker able to control ESI components on an HTTP server could use these flaws to crash Squid, disclose parts of the stack memory, or possibly execute arbitrary code as the user running Squid. (CVE-2016-4052, CVE-2016-4053, CVE-2016-4054)
• An input validation flaw was found in Squid's mime_get_header_field() function, which is used to search for headers within HTTP requests. An attacker could send an HTTP request from the client side with specially crafted header Host header that bypasses same-origin security protections, causing Squid operating as interception or reverse-proxy to contact the wrong origin server. It could also be used for cache poisoning for client not following RFC 7230. (CVE-2016-4554)
• An incorrect reference counting flaw was found in the way Squid processes ESI responses. If Squid is configured as reverse-proxy, for TLS/HTTPS interception, an attacker controlling a server accessed by Squid, could crash the squid worker, causing a Denial of Service attack. (CVE-2016-4556)

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 this update, the squid service 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 for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1329126 - CVE-2016-4051 squid: buffer overflow in cachemgr.cgi
• BZ - 1329136 - CVE-2016-4052 CVE-2016-4053 CVE-2016-4054 squid: multiple issues in ESI processing
• BZ - 1334241 - CVE-2016-4554 squid: Header Smuggling issue in HTTP Request processing
• BZ - 1334786 - CVE-2016-4556 squid: SIGSEGV in ESIContext response handling

CVEs

• CVE-2016-4051
• CVE-2016-4052
• CVE-2016-4053
• CVE-2016-4054
• CVE-2016-4554
• CVE-2016-4556

References

• http://www.redhat.com/security/updates/classification/#normal