#VU30985 Input validation error in Knot Resolver - CVE-2019-10190

Vulnerability identifier: #VU30985

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-10190

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Knot Resolver
Server applications / Other server solutions

Vendor: Nic

Description

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

A vulnerability was discovered in DNS resolver component of knot resolver through version 3.2.0 before 4.1.0 which allows remote attackers to bypass DNSSEC validation for non-existence answer. NXDOMAIN answer would get passed through to the client even if its DNSSEC validation failed, instead of sending a SERVFAIL packet. Caching is not affected by this particular bug but see CVE-2019-10191.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Knot Resolver: 4.0.0

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-10190
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TMSSWBHINIX4WE6UDXWM66L7JYEK6XS6/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VZV5YZZ5766UIG2TFLFJL6EESQNAP5X5/
https://www.knot-resolver.cz/2019-07-10-knot-resolver-4.1.0.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.