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Advisory severityHigh7.5Red Hat Linux

High [CVE-2026-11721] Cache poisoning via label count discrepancy, RRSIG, wildcards

This high-severity Red Hat Linux advisory covers CVE-2026-11721 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7 Extended Lifecycle Support, Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-11721 Source published Source updated

VulniPulse record published Record updated

CVE-2026-11721
Affected products & platforms
Red Hat LinuxRed Hat Enterprise Linux
Open source advisory

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Summary

It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning.

For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N). Weakness: CWE-345.

Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 7 Extended Lifecycle Support; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On; Red Hat Enterprise Linux 8.8 Telecommunications Update Service; Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.6 Extended Update Support; Red Hat OpenShift Container Platform 4.22; Red Hat Hardened Images; Red Hat Enterprise Linux 6; Red Hat OpenShift Container Platform 4.

Affected versions
  • 9.11.0
  • 9.18.50
  • 9.20.0
  • 9.20.24
  • 9.21.0
  • 9.21.23
  • 9.11.3
  • 9.20.9

Official advisory · high-confidence parse· fetched 15 hours ago·verify at source

Fixed versions
  • bind-32:9.18.33-15.el10_2.10
  • bind-32:9.11.4-26.P2.el7_9.21
  • bind9.16-32:9.16.23-0.22.el8_10.12
  • bind-32:9.11.36-16.el8_10.14
  • bind9.16-32:9.16.23-0.7.el8_6.11
  • bind9.16-32:9.16.23-0.14.el8_8.9
  • bind-32:9.16.23-40.el9_8.8
  • bind9.18-32:9.18.29-14.el9_8.8
  • bind-32:9.16.23-18.el9_4.12
  • bind-32:9.16.23-31.el9_6.4
  • openshift/ose-rhel-coreos-9:4.22.9.8.202608191915-0
  • openshift/ose-rhel-coreos-9:4.22.9.8.202609081748-0
  • bind-main-9.20.26-0.1.hum1
  • RHSA-2026:55437
  • RHSA-2026:60383
  • RHSA-2026:54509
  • RHSA-2026:54654
  • RHSA-2026:80501
  • RHSA-2026:79160
  • RHSA-2026:54510
  • RHSA-2026:55442
  • RHSA-2026:57189
  • RHSA-2026:55441
  • RHSA-2026:57362
  • RHSA-2026:66357
  • RHSA-2026:54071

Official advisory · high-confidence parse· fetched 15 hours ago·verify at source

Mitigation

Upgrade to a fixed release: bind-32:9.18.33-15.el10_2.10, bind-32:9.11.4-26.P2.el7_9.21, bind9.16-32:9.16.23-0.22.el8_10.12, bind-32:9.11.36-16.el8_10.14, bind9.16-32:9.16.23-0.7.el8_6.11, bind9.16-32:9.16.23-0.14.el8_8.9. That is the remediation for this advisory.

The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.

Official advisory · high-confidence parse· fetched 15 hours ago·verify at source

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