[squid-announce] [ADVISORY] SQUID-2019:8 Multiple issues in URI processing

[Amos Jeffries]

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    Squid Proxy Cache Security Update Advisory SQUID-2019:8
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Advisory ID:        SQUID-2019:8
Date:               November 05, 2019
Summary:            Multiple issues in URI processing.
Affected versions:  Squid 3.x -> 3.5.28
                    Squid 4.x -> 4.8
Fixed in version:   Squid 4.9
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    http://www.squid-cache.org/Advisories/SQUID-2019_8.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-12523
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18676
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Problem Description:

 Due to improper input validation Squid is vulnerable to security
 bypass attacks. Attacker can gain access to restricted HTTP
 servers.

 Due to incorrect input validation Squid is vulnerable to a buffer
 overflow which can result in Denial of Service to all clients
 using the proxy.

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Severity:

 Any remote client may access resources which should be restricted
 and not available to them. Such as those protected behind client
 IP ACLs. Attacker could also gain access to manager services when
 Via header is turned off.

 Any remote client can perform a Denial of Service on all other
 clients using the proxy.

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Updated Packages:

 These bugs are fixed by Squid version 4.9.

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

Squid 4:
 <http://www.squid-cache.org/Versions/v4/changesets/squid-4-fbbdf75efd7a5cc244b4886a9d42ea458c5a3a73.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:

Use the command 'squid -v' to view version and build details of
your proxy;

 All Squid 2.x have not been checked.

 All Squid-3.x up to and including 3.5.28 are vulnerable.

 All Squid-4.x up to and including 4.8 are vulnerable.

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Workaround:

 Access to manager services can be prevented by enabling the Via
 header:
   via on

 There are no reliable workarounds to prevent access to restricted
 upstream servers.

 There are no workarounds for the Denial of Service issue.

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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 you install and build Squid from the original Squid sources
 then the squid-users at 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 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 at squid-cache.org mailing list. It is 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:

 The security bypass vulnerability was discovered by Jeriko One
 <jeriko.one at gmx.us>.

 The Denial of Service vulnerability was discovered by Kristoffer
 Danielsson.

 Fixed by Amos Jeffries, Treehouse Networks Ltd.

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Revision history:

 2019-05-14 14:56:49 UTC Initial Report
 2019-06-05 15:52:17 UTC CVE-2019-12523 Assignment
 2019-07-03 01:07:41 UTC Additional Report
 2019-11-04 13:43:22 UTC CVE-2019-18676 Assignment
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END