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CVE-2026-11721

Cache poisoning possible with label count discrepancy, RRSIG, and wildcards

Published: Jul 22, 2026Updated: Jul 22, 2026 Sources: CVE List NVDCWE-1284
7.5HIGH
NVD MITRE
EPSS Score
0.4%
Top 68.9%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available
Self-Check
OpenVAS

Description

It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
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:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-1284

Affected Products

ISC
commercial·USaka internet systems consortium
BIND 9
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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References

https://downloads.isc.org/isc/bind9/9.20.26
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.21.24
downloads.isc.org
https://kb.isc.org/docs/cve-2026-11721
kb.isc.org

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