Squid Proxy Cache Security Update Advisory SQUID-2016:11

Advisory ID:        SQUID-2016:11
Date:               Dec 16, 2016
Summary:            Information disclosure
                    in HTTP Request processing.
Affected versions:  Squid 2.6 -> 2.7.STABLE9
                    Squid 3.1 -> 3.5.22
                    Squid 4.0 -> 4.0.16
Fixed in version:   Squid 4.0.17, 3.5.23


Problem Description:

 Due to incorrect HTTP conditional request handling Squid can
 deliver responses containing private data to clients it should
 not have reached.



 This problem allows a remote attacker to discover private and
 sensitive information about another clients browsing session.
 Potentially including credentials which allow access to further
 sensitive resources.


Updated Packages:

 This bug is fixed by Squid version 3.5.23 and 4.0.17.

 In addition, patches addressing this problem can be found in our
 patch archives:

Squid 3.1:

Squid 3.2:

Squid 3.3:

Squid 3.4:

Squid 3.5:

Squid 4.0:

 If you are using a prepackaged version of Squid then please refer
 to the package vendor for availability information on updated


Determining if your version is vulnerable:

 All Squid-2.x versions are not vulnerable.

 All Squid-3.0 are not vulnerable.

 All Squid-3.1 versions up to and including 3.1.9 are not

 All Squid-3.1 versions 3.1.10 and later are vulnerable.

 Squid- and are not vulnerable.

 All Squid-3.2 versions and later are vulnerable.

 All Squid-3.3 versions are vulnerable.

 All Squid-3.4 versions are vulnerable.

 All Squid-3.5 versions up to and including Squid-3.5.22 are

 All Squid-4.0 versions up to and including Squid-4.0.16 are



 The only workaround known is to disable caching, including
 memory cache. In squid.conf set:

   cache deny all
   cache_mem 0


Contact details for the Squid project:

 For installation / upgrade support on binary packaged versions
 of Squid: Your first point of contact should be your binary
 package vendor.

 If your install and build Squid from the original Squid sources
 then the squid-us...@lists.squid-cache.org mailing list is your
 primary support point. For subscription details see

 For reporting of non-security bugs in the latest STABLE release
 the squid bugzilla database should be used

 For reporting of security sensitive bugs send an email to the
 squid-b...@lists.squid-cache.org mailing list. It's a closed
 list (though anyone can post) and security related bug reports
 are treated in confidence until the impact has been established.



 This issue was reported by Saulius Lapinskas from Lithuanian
 State Social Insurance Fund Board.

 Fixed by Garri Djavadyan from iPlus LLC (Comnet ISP).


Revision history:

 2014-12-30 12:44:32 UTC Initial Report
 2016-12-16 18:37:00 UTC Packages Released
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