High severity · published Jul 22, 2026
CVE-2026-11331
Potential wildcard CNAME RPZ policy bypass
7.5
CVSS
0.4%
EPSS
No
On KEV
Description
An attacker who knows (or guesses) that a resolver uses RPZ with wildcard CNAME policies can craft query names long enough to trigger a NAMETOOLONG error condition during RPZ processing. This is not handled correctly and may lead to defeating the RPZ rule. It also may lead to an unexpected exit of the BIND 9 software.
This issue affects BIND 9 versions 9.16.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.16.8-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
B9
BIND 9 · ISC
9.16.0 through 9.18.50; 9.20.0 through 9.20.24; 9.21.0 through 9.21.23; 9.16.8-S1 through 9.18.50-S1; 9.20.9-S1 through 9.20.24-S1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-11331
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-11331
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.20.26
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.21.24
kb.isc.org
https://kb.isc.org/docs/cve-2026-11331
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