Vulnerability identifier: #VU44440

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2011-4869

CWE-ID: CWE-399

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Unbound
Server applications / DNS servers

Vendor: NLnet Labs

Description

The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.

validator/val_nsec3.c in Unbound before 1.4.13p2 does not properly perform proof processing for NSEC3-signed zones, which allows remote DNS servers to cause a denial of service (daemon crash) via a malformed response that lacks expected NSEC3 records, a different vulnerability than CVE-2011-4528.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Unbound: 0.0 - 1.4.11

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External links
http://lists.fedoraproject.org/pipermail/package-announce/2012-January/071525.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-January/071535.html
http://osvdb.org/77910
http://secunia.com/advisories/47326
http://unbound.nlnetlabs.nl/downloads/CVE-2011-4528.txt
http://www.debian.org/security/2011/dsa-2370
http://www.kb.cert.org/vuls/id/209659
http://exchange.xforce.ibmcloud.com/vulnerabilities/71868

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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.