[squid-users] [squid-announce] [ADVISORY] SQUID-2016:4 Denial of Service issue in HTTP Response processing.

Amos Jeffries squid3 at treenet.co.nz
Sat Apr 2 08:25:29 UTC 2016


Squid Proxy Cache Security Update Advisory SQUID-2016:4

Advisory ID:        SQUID-2016:4
Date:               April 02, 2016
Summary:            Denial of Service issue
                    in HTTP Response processing.
Affected versions:  Squid 3.x -> 3.5.15
                    Squid 4.x -> 4.0.7
Fixed in version:   Squid 4.0.8, 3.5.16


Problem Description:

 Due to incorrect bounds checking Squid is vulnerable to a denial
 of service attack when processing HTTP responses.



 This problem allows a malicious client script and remote server
 delivering certain unusual HTTP response syntax to trigger a
 denial of service for all clients accessing the Squid service.


Updated Packages:

 This bug is fixed by Squid version 3.5.16 and 4.0.8.

 In addition, a patch addressing this problem for the stable
 release can be found in our patch archives:

Squid 3.5:

 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 unpatched Squid-3.0 versions are vulnerable.

 All unpatched Squid-3.1 versions are vulnerable.

 All unpatched Squid-3.2 versions are vulnerable.

 All unpatched Squid-3.3 versions are vulnerable.

 All unpatched Squid-3.4 versions are vulnerable.

 All unpatched Squid-3.5 up to and including Squid-3.5.15 are

 All unpatched Squid-4.0 up to and including 4.0.7 are vulnerable.



 There are no good workarounds known for this vulnerability.

 The following squid.conf settings can protect Squid-3.5 (only):

   acl Vary rep_header Vary .
   store_miss deny Vary


 The following squid.conf setting can protect Squid-3.0 or later:

   cache deny all


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-users at 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-bugs at 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 vulnerability was reported by Santiago R. Rincon of Debian.
 Fixed by Amos Jeffries from Treehouse Networks Ltd.


Revision history:

 2016-03-20 11:25:04 UTC Initial Report
 2016-04-01 06:15:31 UTC Patch Released
squid-announce mailing list
squid-announce at lists.squid-cache.org

More information about the squid-users mailing list