Attacker Value
(2 users assessed)
Very High
(2 users assessed)
User Interaction
Privileges Required
Attack Vector

CVE-2020-8616: NXNSAttack: Recursive DNS Inefficiencies and Vulnerabilities

Disclosure Date: May 19, 2020
Add any MITRE ATT&CK Tactics to the list below that apply to this CVE.


A malicious actor who intentionally exploits this lack of effective limitation on the number of fetches performed when processing referrals can, through the use of specially crafted referrals, cause a recursing server to issue a very large number of fetches in an attempt to process the referral. This has at least two potential effects: The performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and The attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor.

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Technical Analysis

This isn’t going to be useful to a pen tester other than a report note, so don’t expect this to get a lot of interest to anyone who is trying to not get noticed. This will be useful I think as a nation-state level attack or in ransom-ware type scenarios, but there are plenty of other DoS techniques out there as well.

General Information


  • ISC


  • BIND9
Technical Analysis