CVE-2026-5946Network attack vectorHinoki check available

DNS service crash via invalid class handling

Published May 20, 2026 · Updated Sep 17, 2026

Assertion failures in named in ISC BIND 9 allow remote attackers to crash the DNS service via crafted DNS messages. Its recursion, UPDATE, NOTIFY, and record-processing paths mishandle non-IN classes or question meta-classes, reaching assertions instead of rejecting incompatible input. Both authoritative servers and resolvers are affected when crafted messages reach these paths; exposure depends on zone classes, update access, and DNS reachability.

CVSS severity7.5
High
EPSS probability1.70%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Assertion failures in named in ISC BIND 9 allow remote attackers to crash the DNS service via crafted DNS messages. Its recursion, UPDATE, NOTIFY, and record-processing paths mishandle non-IN classes or question meta-classes, reaching assertions instead of rejecting incompatible input. Both authoritative servers and resolvers are affected when crafted messages reach these paths; exposure depends on zone classes, update access, and DNS reachability.

The record

CVE
CVE-2026-5946
Published
May 20, 2026
Updated
Sep 17, 2026
Vendor
libuser Project
Product
Red Hat Enterprise Linux 9.6 Extended Update Support
Classifications
CWE-754, CWE-125, CWE-843, CWE-617, CWE-20, CWE-1287, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2026Record 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?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libuser Project · Red Hat Enterprise Linux 9.6 Extended Update SupportAffected versions are unavailable in this record.
libuser Project · Red Hat OpenShift Container PlatformAffected versions are unavailable in this record.
libuser Project · Red Hat OpenShift Container Platform 4Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 7 Extended Lifecycle SupportAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
libuser Project · Red Hat Hardened ImagesAffected versions are unavailable in this record.
Internet Systems Consortium · BIND 9version=9.11.0 <=9.16.50; version=9.11.3-S1 <=9.16.50-S1; version=9.18.0 <=9.18.48; version=9.18.11-S1 <=9.18.48-S1; version=9.20.0 <=9.20.22; version=9.20.9-S1 <=9.20.22-S1; version=9.21.0 <=9.21.21
libuser Project · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux for SAP SolutionsAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 6Affected versions are unavailable in this record.

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
CWE-125Out-of-bounds Read
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
CWE-617Reachable Assertion
CWE-20Improper Input Validation
CWE-1287Improper Validation of Specified Type of Input
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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