CVE-2023-5517Network attack vector

Remote resolver crash via RFC 1918 PTR query

Published Feb 13, 2024 · Updated Feb 13, 2025

Reachable assertion in Internet Systems Consortium BIND 9 affected releases allows remote attackers to crash named with a PTR query. With nxdomain-redirect enabled, query handling for an RFC 1918 reverse zone reaches an assertion while processing an authoritative NXDOMAIN response. The resolver must have the redirect namespace configured; one unauthenticated DNS query then terminates the service.

CVSS severity7.5
High
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in Internet Systems Consortium BIND 9 affected releases allows remote attackers to crash named with a PTR query. With nxdomain-redirect enabled, query handling for an RFC 1918 reverse zone reaches an assertion while processing an authoritative NXDOMAIN response. The resolver must have the redirect namespace configured; one unauthenticated DNS query then terminates the service.

The record

CVE
CVE-2023-5517
Published
Feb 13, 2024
Updated
Feb 13, 2025
Vendor
Internet Systems Consortium
Product
BIND 9
Classifications
CWE-617, 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=9.12.0 <=9.16.45
  2. Affected versionversion=9.16.8-S1 <=9.16.45-S1
  3. Affected versionversion=9.18.0 <=9.18.21
  4. Affected versionversion=9.18.11-S1 <=9.18.21-S1
  5. Affected versionversion=9.19.0 <=9.19.19

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Internet Systems Consortium · BIND 9version=9.12.0 <=9.16.45; version=9.16.8-S1 <=9.16.45-S1; version=9.18.0 <=9.18.21; version=9.18.11-S1 <=9.18.21-S1; version=9.19.0 <=9.19.19

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 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-617Reachable Assertion
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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