Moderate: squid (SL6)

Synopsis: Moderate: squid security and bug fix update
Issue Date: 2013-02-21
CVE Numbers: CVE-2012-5643

A denial of service flaw was found in the way the Squid Cache Manager processed
certain requests. A remote attacker who is able to access the Cache Manager CGI
could use this flaw to cause Squid to consume an excessive amount of memory.

This update also fixes the following bugs:

* Due to a bug in the ConnStateData::noteMoreBodySpaceAvailable() function,
child processes of Squid terminated upon encountering a failed assertion. An
upstream patch has been provided and Squid child processes no longer terminate.

* Due to an upstream patch, which renamed the HTTP header controlling
persistent connections from “Proxy-Connection” to “Connection”, the NTLM pass-
through authentication does not work, thus preventing login. This update adds
the new “http10” option to the squid.conf file, which can be used to enable the
change in the patch. This option is set to “off” by default. When set to “on”,
the NTLM pass-through authentication works properly, thus allowing login
attempts to succeed.

* When the IPv6 protocol was disabled and Squid tried to handle an HTTP GET
request containing an IPv6 address, the Squid child process terminated due to
signal 6. This bug has been fixed and such requests are now handled as

* The old “stale if hit” logic did not account for cases where the stored stale
response became fresh due to a successful re-validation with the origin server.
Consequently, incorrect warning messages were returned. Now, Squid no longer
marks elements as stale in the described scenario.

* When squid packages were installed before samba-winbind, the wbpriv group did
not include Squid. Consequently, NTLM authentication calls failed. Now, Squid
correctly adds itself into the wbpriv group if samba-winbind is installed
before Squid, thus fixing this bug.

* In FIPS mode, Squid was using private MD5 hash functions for user
authentication and network access. As MD5 is incompatible with FIPS mode, Squid
could fail to start. This update limits the use of the private MD5 functions to
local disk file hash identifiers, thus allowing Squid to work in FIPS mode.

* Under high system load, the squid process could terminate unexpectedly with a
segmentation fault during reboot. This update provides better memory handling
during reboot, thus fixing this bug.

* Squid incorrectly set the timeout limit for client HTTP connections with the
value for server-side connections, which is much higher, thus creating
unnecessary delays. With this update, Squid uses a proper value for the client
timeout limit.

* Squid did not properly release allocated memory when generating error page
contents, which caused memory leaks. Consequently, the Squid proxy server
consumed a lot of memory within a short time period. This update fixes this
memory leak.

* Squid did not pass the ident value to a URL rewriter that was configured
using the “url_rewrite_program” directive. Consequently, the URL rewriter
received the dash character (“”) as the user value instead of the correct user
name. Now, the URL rewriter receives the correct user name in the described

* Squid, used as a transparent proxy, can only handle the HTTP protocol.
Previously, it was possible to define a URL in which the access protocol
contained the asterisk character (*) or an unknown protocol namespace URI.
Consequently, an “Invalid URL” error message was logged to access.log during
reload. This update ensures that “http://” is always used in transparent proxy
URLs, and the error message is no longer logged in this scenario.

After installing this update, the squid service will be restarted


– Scientific Linux Development Team