CVE-2026-11331

HIGH 7.5

Potential wildcard CNAME RPZ policy bypass

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-790
Vendor	isc
Product	bind 9
Published	Jul 22, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Affected Versions

ISC / BIND 9

9.16.0 ≤ 9.18.50 9.20.0 ≤ 9.20.24 9.21.0 ≤ 9.21.23 9.16.8-S1 ≤ 9.18.50-S1 9.20.9-S1 ≤ 9.20.24-S1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

kb.isc.org: https://kb.isc.org/docs/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

Credits

ISC would like to thank Laith Mash'al (0xmshal) for bringing this vulnerability to our attention.