CVE-2020-8616Network attack vector

DNS service degradation via unbounded referral fetches

Published May 19, 2020 · Updated Sep 16, 2024

Resource exhaustion in Internet Systems Consortium BIND 9 allows remote attackers to degrade recursive DNS service via crafted referrals. Referral processing fails to cap address-record fetches for delegated name servers, so one response can trigger a cascade of outbound queries. The server must perform recursion; exploitation can consume resolver capacity or turn it into a high-amplification reflector against another target.

CVSS severityUnavailable

Unscored

EPSS probability10.59%

Next 30 days · Sep 16, 2026

Known exploitationUnconfirmed

Based on sourced intelligence

Hinoki checkNot available

Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

The record

CVE: CVE-2020-8616
Published: May 19, 2020
Updated: Sep 16, 2024

Vendor: Internet Systems Consortium
Product: BIND 9
Classifications: CWE-400, T1498.002

Attack vector: network
Privileges: unauthenticated

Timeline

How it unfolded

May 19, 2020CVE publishedPublication date reported by the CVE source.
Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

Affected versionversion=9.0.0 -> 9.11.18, 9.12.0 -> 9.12.4-P2, 9.14.0 -> 9.14.11, 9.16.0 -> 9.16.2, and releases 9.17.0 -> 9.17.1 of the 9.17 experimental development branch. All releases in the obsolete 9.13 and 9.15 development branches. All releases of BIND Supported Preview Edition from 9.9.3-S1 -> 9.11.18-S1

What conditions does exploitation require?

Attack vectornetwork

Required privilegesunauthenticated

What is affected?

Internet Systems Consortium · BIND 9version=9.0.0 -> 9.11.18, 9.12.0 -> 9.12.4-P2, 9.14.0 -> 9.14.11, 9.16.0 -> 9.16.2, and releases 9.17.0 -> 9.17.1 of the 9.17 experimental development branch. All releases in the obsolete 9.13 and 9.15 development branches. All releases of BIND Supported Preview Edition from 9.9.3-S1 -> 9.11.18-S1

Published CVSS scores

8.0Internet Systems ConsortiumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:F/RL:O/RC:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026

Latest reporting daySep 15, 2026

Latest daily unique IPsUnavailable

Prior 30-day averageUnavailable

SourceShadowserver honeypots (KEV)

Vectornetwork

Privilegesunauthenticated

Known exploitationUnconfirmed

Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption

T1498.002Network Denial of Service: Reflection Amplification

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo