How severe is CVE-2026-11331?

CVE-2026-11331 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-11331?

Affected package information for CVE-2026-11331 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-11331?

No fixed release is recorded for CVE-2026-11331 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2026-11331 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2026-11331 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-11331 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-11331 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-11331?

CVE-2026-11331 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 35th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-11331?

CVE-2026-11331 is classified as CWE-790 (CWE-790). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-11331 published, and has it been updated?

CVE-2026-11331 was published on July 22, 2026 and was last updated on July 22, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

Not in CISA KEV

HIGH severity

CVE-2026-11331

HIGH

CVE-2026-11331 is a high-severity (CVSS 7.5) CWE-790 vulnerability. No vendor fix is recorded yet; mitigation options are listed below.

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.…

Published

Jul 22, 2026

Updated

Jul 22, 2026

Affected

—

Patched

—

Exploits

None indexed

Exploitation data as of Sep 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-11331.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs35th percentile — riskier than 35% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-11331 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

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.

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2026-11331 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

Product	Fixed in	Advisory
Red Hat Enterprise Linux 10	`bind-32:9.18.33-15.el10_2.10`	RHSA-2026:55437
Red Hat Enterprise Linux 8	`bind9.16-32:9.16.23-0.22.el8_10.12`	RHSA-2026:54509
Red Hat Enterprise Linux 9	`bind-32:9.16.23-40.el9_8.8`	RHSA-2026:54510
Red Hat Enterprise Linux 9	`bind9.18-32:9.18.29-14.el9_8.8`	RHSA-2026:55442
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions	`bind-32:9.16.23-18.el9_4.12`	RHSA-2026:57189
Red Hat Enterprise Linux 9.6 Extended Update Support	`bind-32:9.16.23-31.el9_6.4`	RHSA-2026:55441
Red Hat OpenShift Container Platform 4.16	`rhcos-416.94.202609011112-0`	RHSA-2026:62549
Red Hat OpenShift Container Platform 4.18	`rhcos-418.94.202609031320-0`	RHSA-2026:65851

UbuntuHIGH

USN-8648-1Ubuntu

Frequently Asked Questions

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