Vulnerability identifier: #VU32370

Vulnerability risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2015-5400

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Squid
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: Squid-cache.org

Description

The vulnerability allows a remote non-authenticated attacker to read and manipulate data.

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Squid: 3.5.0.1 - 3.5.5

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External links
http://lists.fedoraproject.org/pipermail/package-announce/2016-May/183598.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
http://www.debian.org/security/2015/dsa-3327
http://www.openwall.com/lists/oss-security/2015/07/06/8
http://www.openwall.com/lists/oss-security/2015/07/09/12
http://www.openwall.com/lists/oss-security/2015/07/10/2
http://www.openwall.com/lists/oss-security/2015/07/17/14
http://www.securityfocus.com/bid/75553
http://www.securitytracker.com/id/1032873
http://www.squid-cache.org/Advisories/SQUID-2015_2.txt
http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10494.patch
http://www.squid-cache.org/Versions/v3/3.4/changesets/squid-3.4-13225.patch
http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13856.patch

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.