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CVE-2026-5947

SIG(0) validation during query flood may lead to undefined behavior

Published: May 20, 2026Updated: Jul 23, 2026 Sources: CVE List NVDCWE-362
7.5HIGH
NVD MITRE
EPSS Score
1.4%
Top 30.4%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available
Self-Check
OpenVAS

Description

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

No summary for this CVE yet.

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
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Weaknesses

CWE-362CWE-416CWE-367

Affected Products

ISC
commercial·USaka internet systems consortium
BIND 9
Networking Infrastructure
bind
Networking Infrastructure

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
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
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References

https://kb.isc.org/docs/cve-2026-5947
kb.isc.org
https://downloads.isc.org/isc/bind9/9.20.23
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.21.22
downloads.isc.org
and 4 more references View all →
News mentions
1

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