#VU29237 Buffer overflow in Unbound - CVE-2019-16866

Vulnerability identifier: #VU29237

Vulnerability risk: Medium

CVSSv4.0: 4.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-16866

CWE-ID: CWE-119

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Unbound
Server applications / DNS servers

Vendor: NLnet Labs

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack

The vulnerability exists due to a boundary error when processing NOTIFY queries in Unbound. A remote attacker can send a specially crafted NOTIFY query, trigger uninitialized memory access and crash the service.

Successful exploitation of this vulnerability requires that the source IP address of the query matches an access-control rule.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Unbound: 1.9.0 rc1 - 1.9.3

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External links
https://github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/E65NCWZZB2D75ZIYWPXKMVGSGNYW4JMC/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MLRHE7TQFAOV4MB2ELTOGESZYUL65NUJ/
https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt
https://seclists.org/bugtraq/2019/Oct/23
https://usn.ubuntu.com/4149-1/
https://www.debian.org/security/2019/dsa-4544

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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.