Vulnerability identifier: #VU44514

Vulnerability risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2011-4096

CWE-ID: CWE-399

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 perform service disruption.

The idnsGrokReply function in Squid before 3.1.16 does not properly free memory, which allows remote attackers to cause a denial of service (daemon abort) via a DNS reply containing a CNAME record that references another CNAME record that contains an empty A record.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Squid: 3.0 - 3.1.14

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External links
http://bugs.squid-cache.org/show_bug.cgi?id=3237#c12
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
http://secunia.com/advisories/46609
http://secunia.com/advisories/47459
http://www.mandriva.com/security/advisories?name=MDVSA-2011:193
http://www.openwall.com/lists/oss-security/2011/10/31/5
http://www.openwall.com/lists/oss-security/2011/11/01/3
http://www.redhat.com/support/errata/RHSA-2011-1791.html
http://www.securitytracker.com/id?1026265
http://www.squid-cache.org/Versions/v3/3.1/changesets/SQUID_3_1_16.html

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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.