CVE-2023-6516Network attack vector

Remote DNS interruption via unbounded cleanup queue

Published Feb 13, 2024 · Updated Feb 13, 2025

Resource exhaustion in Internet Systems Consortium BIND 9 9.16.0 through 9.16.45 allows remote attackers to interrupt DNS service. The named recursive resolver allocates cleanup-event records faster than asynchronous cache maintenance consumes them, allowing the queue and memory use to grow beyond the configured max-cache-size bound. Sustained triggering query patterns and environmental conditions determine effectiveness; exhaustion can consume host memory and stop DNS resolution.

CVSS severity7.5
High
EPSS probability1.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Internet Systems Consortium BIND 9 9.16.0 through 9.16.45 allows remote attackers to interrupt DNS service. The named recursive resolver allocates cleanup-event records faster than asynchronous cache maintenance consumes them, allowing the queue and memory use to grow beyond the configured max-cache-size bound. Sustained triggering query patterns and environmental conditions determine effectiveness; exhaustion can consume host memory and stop DNS resolution.

The record

CVE
CVE-2023-6516
Published
Feb 13, 2024
Updated
Feb 13, 2025
Vendor
Internet Systems Consortium
Product
BIND 9
Classifications
CWE-770, CWE-789, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 13, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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=9.16.0 <=9.16.45
  2. Affected versionversion=9.16.8-s1 <=9.16.45-s1
  3. Affected versionversion=9.16.8-S1 <=9.16.45-S1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Internet Systems Consortium · BIND 9version=9.16.0 <=9.16.45; version=9.16.8-s1 <=9.16.45-s1; version=9.16.8-S1 <=9.16.45-S1

Published CVSS scores

7.5Internet 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

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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