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    Squid Proxy Cache Security Update Advisory SQUID-2018:4
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Advisory ID:        SQUID-2018:4
Date:               October 28, 2018
Summary:            Cross-Site Scripting issue
                    in TLS error processing.
Affected versions:  Squid 3.1.12.1 -> 3.1.23
                    Squid 3.2.0.4 -> 3.5.28
                    Squid 4.0 -> 4.3
Fixed in version:   Squid 4.4
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    http://www.squid-cache.org/Advisories/SQUID-2018_4.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-19131
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Problem Description:

 Due to incorrect input handling, Squid is vulnerable to a
 Cross-Site Scripting vulnerability when generating HTTPS response
 messages about TLS errors.

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Severity:

 This problem allows a malicious HTTPS server to trigger error
 page delivery to a client and also inject arbitrary HTML code
 into the resulting error response.

 This problem is limited to Squid built with TLS / SSL support.

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Updated Packages:

 This bug is fixed by Squid version 4.4.

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

Squid 3.5:
 http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-f1657a9decc820f748fa3aff68168d3145258031.patch

Squid 4:
 http://www.squid-cache.org/Versions/v4/SQUID-2018_4.patch

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

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Determining if your version is vulnerable:

 All Squid-2.x and older are not vulnerable.

 All Squid-3.0 and older version are not vulnerable.

 All Squid-3.x versions up to and including 3.4.14 built with
 --disable-ssl are not vulnerable.

 All Squid-3.x versions up to and including 3.4.14 built without
 --enable-ssl are not vulnerable.

 All Squid-3.1.12.1 and later versions up to and including
 Squid-3.1.23 built with --enable-ssl are vulnerable.

 All Squid-3.2.0.4 and later versions up to and including
 Squid-3.2.14 built with --enable-ssl are vulnerable.

 All Squid-3.3 and later versions up to and including
 Squid-3.3.14 built with --enable-ssl are vulnerable.

 All Squid-3.4 and later versions up to and including
 Squid-3.4.14 built with --enable-ssl are vulnerable.

 All Squid-3.5 versions up to and including 3.5.28 built without
 --with-openssl are not vulnerable.

 All Squid-3.5 and later versions up to and including 3.5.28 built
 with --with-openssl are vulnerable.

 All Squid-4 versions built without --with-openssl are not
 vulnerable.

 All Squid-4 versions up to and including 4.3 built with
 --with-openssl are vulnerable.

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Workarounds:

Either;

 Remove %D error page macro from ERR_SECURE_CONNECT_FAIL and any
 custom error pages.

Or,

 Build Squid-3.1 to 3.4.14 without "--enable-ssl"

Or,

 Build Squid-3.5 or later without "--with-openssl"

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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
 <http://www.squid-cache.org/Support/mailing-lists.html>.

 For reporting of non-security bugs in the latest STABLE release
 the squid bugzilla database should be used
 <http://bugs.squid-cache.org/>.

 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.

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Credits:

 This vulnerability was discovered by Nikolas Lohmann of eBlocker
 GmbH.

 Fixed by Christos Tsantilas on behalf of Measurement Factory.

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Revision history:

 2018-10-15 10:59:16 UTC Initial Report
 2018-10-17 15:13:41 UTC Patches Released
 2018-10-27 21:19:00 UTC Packages Released
 2018-11-09 12:45:01 UTC CVE Assignment
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