CVE-2023-5680Network attack vector

Resolver denial of service via ECS cache cleanup

Published Feb 13, 2024 · Updated Mar 17, 2025

Denial of service in Internet Systems Consortium BIND 9 allows remote attackers to make recursive resolvers unresponsive. Specific queries accumulate a very large number of EDNS Client Subnet records under one cache name, making node cleanup consume enough CPU to impair query handling. The gate is an ECS-enabled resolver running 9.11.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.45-S1, or 9.18.11-S1 through 9.18.21-S1; named can become entirely unresponsive.

CVSS severity5.3
Medium
EPSS probability0.63%
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 make recursive resolvers unresponsive. Specific queries accumulate a very large number of EDNS Client Subnet records under one cache name, making node cleanup consume enough CPU to impair query handling. The gate is an ECS-enabled resolver running 9.11.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.45-S1, or 9.18.11-S1 through 9.18.21-S1; named can become entirely unresponsive.

The record

CVE
CVE-2023-5680
Published
Feb 13, 2024
Updated
Mar 17, 2025
Vendor
Internet Systems Consortium
Product
BIND 9
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 13, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 17, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=9.11.3-S1 <=9.11.37-S1
  2. Affected versionversion=9.16.8-S1 <=9.16.45-S1
  3. Affected versionversion=9.18.11-S1 <=9.18.21-S1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Internet Systems Consortium · BIND 9version=9.11.3-S1 <=9.11.37-S1; version=9.16.8-S1 <=9.16.45-S1; version=9.18.11-S1 <=9.18.21-S1

Published CVSS scores

5.3Internet Systems ConsortiumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation Flood

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

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Your stack

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