CVE-2026-11331

MEDIUM

7.5

CVSS v3

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.

CWE-790

How to fix

Remediation Available

bind9Debian

Fixed in:1:9.16.50-1~deb11u6CVE-2026-11331

Fixed in:1:9.18.49-1~deb12u2CVE-2026-11331

Fixed in:1:9.20.26-1~deb13u1CVE-2026-11331

Fixed in:1:9.20.26-1CVE-2026-11331

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.42%probability of exploitation in 30 days

34thpercentile

Low risk: more likely to be exploited than 34% of all known CVEs.

References

Other references3

Related Vulnerabilities

Other CWE-790 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2021-43802	Critical	9.9	2.0%	-	Fix
CVE-2023-45239	Critical	9.8	1.8%	-	Fix
CVE-2024-31616	High	8.8	0.8%	-	-
CVE-2023-22578	Critical	10.0	0.8%	-	Fix
CVE-2024-47984	Medium	4.4	0.5%	-	-
CVE-2024-43442	Medium	4.9	0.4%	-	-

Common questions

How do I fix CVE-2026-11331?

Upgrade bind9 on debian 11 to 1:9.16.50-1~deb11u6 or later.

Is CVE-2026-11331 being actively exploited?

Not that we know of. CVE-2026-11331 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.42% is the estimated probability that it will be exploited in the next 30 days. That is higher than 34% of all scored CVEs.

How severe is CVE-2026-11331?

CVE-2026-11331 has a CVSS v3 base score of 7.5, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-11331 affect?

Published advisories record a fix for bind9 (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-22.