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Vulnerabilities

Vulnerability · CVE-2026-11331

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 proce

Published Jul 22, 2026 · catalog updated Oct 17, 2026 · Canonical Ubuntu

Check if you run it

No confirmed exploitation is on record for CVE-2026-11331. EPSS is 0.43%. Act only if a listed version of Canonical Ubuntu is installed.

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.43%
Remediation
Advisory link
Affected products
Ubuntu:18.04:LTS isc-dhcp · Ubuntu:20.04:LTS bind9-libs · Ubuntu:22.04:LTS bind9 · Ubuntu:22.04:LTS bind9-libs · Ubuntu:24.04:LTS bind9 · Ubuntu:24.04:LTS isc-dhcp

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Ubuntu:18.04:LTS isc-dhcp4.3.5-3ubuntu2, 4.3.5-3ubuntu3, 4.3.5-3ubuntu4
  • Ubuntu:20.04:LTS bind9-libs1:9.11.16+dfsg-3~build1, 1:9.11.16+dfsg-3~ubuntu1
  • Ubuntu:22.04:LTS bind90 → 1:9.18.39-0ubuntu0.22.04.5
  • Ubuntu:22.04:LTS bind9-libs1:9.11.19+dfsg-2.1ubuntu1, 1:9.11.19+dfsg-2.1ubuntu2, 1:9.11.19+dfsg-2.1ubuntu3
  • Ubuntu:24.04:LTS bind90 → 1:9.18.39-0ubuntu0.24.04.6
  • Ubuntu:24.04:LTS isc-dhcp4.4.3-P1-2ubuntu5, 4.4.3-P1-4ubuntu1, 4.4.3-P1-4ubuntu2
  • Ubuntu:26.04:LTS bind90 → 1:9.20.24-1ubuntu0.2
  • Ubuntu:26.04:LTS isc-dhcp4.4.3-P1-4ubuntu2
  • Ubuntu:Pro:20.04:LTS bind90 → 1:9.18.30-0ubuntu0.20.04.2+esm3

How to fix CVE-2026-11331

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-11331. EPSS is 0.43%. Act only if a listed version of Canonical Ubuntu is installed.

Which versions are affected?

Compare what you have installed with 4.3.5-3ubuntu2, 4.3.5-3ubuntu3, 4.3.5-3ubuntu4, 1:9.11.16+dfsg-3~build1, 1:9.11.16+dfsg-3~ubuntu1, 0 → 1:9.18.39-0ubuntu0.22.04.5, 1:9.11.19+dfsg-2.1ubuntu1, 1:9.11.19+dfsg-2.1ubuntu2, 1:9.11.19+dfsg-2.1ubuntu3, 0 → 1:9.18.39-0ubuntu0.24.04.6, 4.4.3-P1-2ubuntu5, 4.4.3-P1-4ubuntu1, 4.4.3-P1-4ubuntu2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.43%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 14, 2026 · Ubuntu Security Notices

    Detected

    Zuyao Xu and Xiang Li discovered that Bind incorrectly handled certain malformed DNSKEY records. A remote attacker could possibly use this issue to cause Bind to consume resources, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 18.04 LTS. (CVE-2025-8677) Yuxiao Wu, Yunyi Zhang, Baojun Liu, and Haixin Duan discovered that Bind incorrectly a

  2. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    bind9 fixed in 1:9.18.30-0ubuntu0.20.04.2+esm3; bind9 fixed in 1:9.18.39-0ubuntu0.22.04.5; bind9 fixed in 1:9.18.39-0ubuntu0.24.04.6; bind9 fixed in 1:9.20.24-1ubuntu0.2

  3. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    bind9 fixed in 1:9.18.30-0ubuntu0.20.04.2+esm3

  4. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    bind9 fixed in 1:9.18.39-0ubuntu0.22.04.5

  5. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    bind9 fixed in 1:9.18.39-0ubuntu0.24.04.6

  6. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    bind9 fixed in 1:9.20.24-1ubuntu0.2

  7. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    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 9.20.2

  8. Oct 17, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    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 9.20.2

Sources

  • CVE.orgVulnerability recordCVE-2026-11331

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-11331

    30-day exploitation probability 0.4%

    first.org
  • OpenSSF OSV / OSV ScannerPackage advisoryUBUNTU-CVE-2026-11331
    osv.dev
  • Ubuntu Security NoticesVendor advisoryCVE-2026-11331

    Zuyao Xu and Xiang Li discovered that Bind incorrectly handled certain malformed DNSKEY records. A remote attacker could possibly use this issue to cause Bind to consume resources, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, and

    ubuntu.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.