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             AUSCERT External Security Bulletin Redistribution

          Squid Proxy Cache Security Update Advisory SQUID-2019:4
                               20 April 2020


        AusCERT Security Bulletin Summary

Product:           Squid Proxy Cache
Publisher:         Squid
Operating System:  UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Cross-site Scripting -- Remote with User Interaction
                   Reduced Security     -- Remote/Unauthenticated      
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-12524 CVE-2019-12520 

Original Bulletin: 

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    Squid Proxy Cache Security Update Advisory SQUID-2019:4

Advisory ID:        SQUID-2019:4
Date:               April 18, 2020
Summary:            Multiple Issues
                    in HTTP Request processing.
Affected versions:  Squid 3.5.18 -> 3.5.28
                    Squid 4.0.10 -> 4.7
Fixed in version:   Squid 4.8


Problem Description:

 Due to incorrect URL handling Squid is vulnerable to access
 control bypass, cache poisoning and cross-site scripting attacks
 when processing HTTP Request messages.


 A remote client can deliver crafted URLs to bypass cache manager
 security controls and retrieve confidential details about the
 proxy and traffic it is handling.

 A remote client can deliver crafted URLs which cause arbitrary
 content from one origin server to be stored in cache as URLs
 within another origin. This opens a window of opportunity for
 clients to be tricked into fetching and XSS execution of that
 content via side channels.

Updated Packages:

 This bug is fixed by Squid version 4.8.

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

Squid 4:

 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 are not vulnerable.

 All Squid-3.x up to and including 3.5.17 are not vulnerable.

 All Squid-3.5.18 up to and including 3.5.28 are vulnerable.

 All Squid-4.x up to and including 4.0.9 are not vulnerable.

 All Squid-4.x up to and including 4.7 without HTTPS support are
 not vulnerable.

 All Squid-4.0.10 up to and including 4.7 with HTTPS support are


 There are no workarounds for Squid-3.5.

 For Squid-4 build using --without-openssl --without-gnutls

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@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@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 discovered by Jeriko One

 Fixed by Amos Jeffries of Treehouse Networks Ltd.

Revision history:

 2019-05-14 14:56:49 UTC Initial Report
 2019-06-23 15:15:56 UTC Patches Released
 2019-06-05 15:52:17 UTC CVE Assignment


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