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CVE-2026-5946

Invalid handling of CLASS != IN

Published: May 20, 2026Updated: May 20, 2026 Sources: CVE List NVD
NVD MITRE
7.5CVSS
HIGH

Multiple flaws have been identified in `named` related to the handling of DNS messages whose CLASS is not Internet (`IN`) — for example, `CHAOS` or `HESIOD`, or DNS messages that specify meta-classes (`ANY` or `NONE`) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (`UPDATE`), zone change notifications (`NOTIFY`), or processing of `IN`-specific record types in non-`IN` data — can cause assertion failures in `named`. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High

Weaknesses

CWE-20CWE-125CWE-617CWE-754CWE-843

Affected Products

BIND 9
ISC

Attack Graph

Products CVE Techniques Tactics

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Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Workaround Available

MITRE ATT&CK

4 techniques
Collection
Impact
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://kb.isc.org/docs/cve-2026-5946
kb.isc.org
https://downloads.isc.org/isc/bind9/9.18.49
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.20.23
downloads.isc.org
and 1 more references View all →

Timeline

Published
May 20, 2026
Last Updated
May 20, 2026

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