CVE-2020-8617Public exploitNetwork attack vector

Server crash via inconsistent TSIG validation state

Published May 19, 2020 · Updated Sep 16, 2024

Denial of service in Internet Systems Consortium BIND 9 allows remote attackers to crash named with a crafted TSIG-bearing DNS message. TSIG record validation mishandles the message and leaves server state inconsistent, after which an assertion in tsig.c terminates the process. The packet must reach the DNS service and name an existing TSIG key; the default local session key exposes almost all installations.

CVSS severity7.0
High
EPSS probability93.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Internet Systems Consortium BIND 9 allows remote attackers to crash named with a crafted TSIG-bearing DNS message. TSIG record validation mishandles the message and leaves server state inconsistent, after which an assertion in tsig.c terminates the process. The packet must reach the DNS service and name an existing TSIG key; the default local session key exposes almost all installations.

The record

CVE
CVE-2020-8617
Published
May 19, 2020
Updated
Sep 16, 2024
Vendor
Internet Systems Consortium
Product
BIND 9
Classifications
CWE-617, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 19, 2020CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. 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

7.0Internet Systems ConsortiumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499Endpoint Denial of Service

Public exploit references

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

Technologies

Your stack

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Your stack

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