#VU28141 Input validation error in PowerDNS Recursor - CVE-2020-10995

Vulnerability identifier: #VU28141

Vulnerability risk: Medium

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

CVE-ID: CVE-2020-10995

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
PowerDNS Recursor
Server applications / DNS servers

Vendor: PowerDNS.COM B.V.

Description

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

The vulnerability exists due to insufficient validation of user-supplied input when processing DNS responses. A remote attacker who controls a malicious DNS server can send a specially crafted response and perform a denial of service (DoS) attack against third-party DNS servers.

The attack is triggered by random subdomains in the NSDNAME in NS records.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

PowerDNS Recursor: 4.1.0 rc1 - 4.1.15, 4.2.0 alpha1 - 4.2.1, 4.3.0 rc1 - 4.3.0

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External links
https://www.nxnsattack.com
https://doc.powerdns.com/recursor/security-advisories/powerdns-advisory-2020-01.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.