Input validation error in ISC BIND - CVE-2026-11721

Vulnerability identifier: #VU139209

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-11721

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to poison the DNS cache.

The vulnerability exists due to improper input validation in named when processing DNS responses containing an RRSIG with fewer labels than the containing zone and wildcard records. A remote attacker can operate an authoritative zone that returns a specially crafted response to poison the DNS cache.

The issue has effect only when the resolver under attack has synth-from-dnssec yes; enabled, which is the default.

ISC BIND
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
Debian Linux
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Micro
SUSE Multi-Linux Manager Client Tools for SLE Micro
SUSE Manager Client Tools for SLE Micro
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for x86_64
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for ARM 64
Anolis OS
Red Hat CodeReady Linux Builder for IBM z Systems
Red Hat Enterprise Linux Server - AUS
Basesystem Module
Server Applications Module
openSUSE Leap
openEuler
Ubuntu
Fedora
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
bind (Red Hat package) main
bind-libs-lite
python3-bind
bind-utils
bind-pkcs11-devel
bind-pkcs11
bind-libs
bind-export-libs
bind-export-devel
bind-devel
bind-debugsource
bind-debuginfo
bind-chroot
bind
libisccfg163
liblwres161
libisccfg163-debuginfo
libisc1107
libbind9-161-debuginfo
bind-chrootenv
libisccc161-debuginfo
libirs161-debuginfo
libirs161
liblwres161-debuginfo
libdns1110-debuginfo
bind-utils-debuginfo
python-bind
bind-doc
libisc1107-32bit
libisc1107-debuginfo-32bit
libbind9-161
libdns1110
libisccc161
libisc1107-debuginfo
bind-license
bind-sdb-chroot
bind-sdb
bind-pkcs11-utils
bind-pkcs11-libs
bind-lite-devel
libirs1601-debuginfo
libisc1606
libisccfg1600-64bit
libirs1601-64bit
libisccc1600-64bit
libdns1605-64bit
libisc1606-64bit
libbind9-1600-64bit
libdns1605-debuginfo
libisccc1600-debuginfo
libbind9-1600-debuginfo
libisc1606-debuginfo
libisccc1600
libisccfg1600
libdns1605
libirs1601
libisccfg1600-debuginfo
libbind9-1600
libns1604-debuginfo
libns1604
libirs-devel
bind9.16-license
python3-bind9.16
bind9.16
bind9.16-chroot
bind9.16-devel
bind9.16-dnssec-utils
bind9.16-libs
bind9.16-utils
bind9.16-doc
bind9.16 (Red Hat package)
bind-dnssec-utils
bind-dnssec-doc
bind9 (Ubuntu package)
bind9 (Debian package)
Red Hat OpenShift Container Platform

Install security update from vendor's website.

ISC BIND - addressed in versions 9.20.26, 9.20.26-s1, 9.21.24
Red Hat OpenShift Container Platform - update to 4.22.11
bind (Red Hat package) main - addressed in versions 9.11.4-26.P2.el7_9.21, 9.11.36-16.el8_10.14, 9.16.23-18.el9_4.12, 9.16.23-40.el9_8.8
bind-libs-lite - update to 9.11.21-25
python3-bind - addressed in versions 9.11.21-25, 9.16.23-31
bind-utils - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-pkcs11-devel - addressed in versions 9.11.21-25, 9.16.23-31
bind-pkcs11 - addressed in versions 9.11.21-25, 9.16.23-31
bind-libs - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-export-libs - update to 9.11.21-25
bind-export-devel - update to 9.11.21-25
bind-devel - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-debugsource - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-debuginfo - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-chroot - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
bind - addressed in versions 9.11.21-25, 9.16.23-31, 9.18.21-11, 9.20.21-4
libisccfg163 - update to 9.11.22-3.74.1
liblwres161 - update to 9.11.22-3.74.1
bind-debuginfo - addressed in versions 9.11.22-3.74.1, 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1, 9.18.50-150600.3.32.1, 9.20.26-150700.3.29.1
libisccfg163-debuginfo - update to 9.11.22-3.74.1
libisc1107 - update to 9.11.22-3.74.1
libbind9-161-debuginfo - update to 9.11.22-3.74.1
bind - addressed in versions 9.11.22-3.74.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1, 9.18.50-150600.3.32.1, 9.20.26-150700.3.29.1
bind-chrootenv - addressed in versions 9.11.22-3.74.1, 9.16.6-150300.22.62.1
libisccc161-debuginfo - update to 9.11.22-3.74.1
libirs161-debuginfo - update to 9.11.22-3.74.1
libirs161 - update to 9.11.22-3.74.1
liblwres161-debuginfo - update to 9.11.22-3.74.1
libdns1110-debuginfo - update to 9.11.22-3.74.1
bind-debugsource - addressed in versions 9.11.22-3.74.1, 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1, 9.18.50-150600.3.32.1, 9.20.26-150700.3.29.1
bind-utils-debuginfo - addressed in versions 9.11.22-3.74.1, 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1, 9.18.50-150600.3.32.1, 9.20.26-150700.3.29.1
python-bind - update to 9.11.22-3.74.1
bind-doc - addressed in versions 9.11.22-3.74.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1, 9.18.50-150600.3.32.1, 9.20.26-150700.3.29.1
libisc1107-32bit - update to 9.11.22-3.74.1
libisc1107-debuginfo-32bit - update to 9.11.22-3.74.1
libbind9-161 - update to 9.11.22-3.74.1
libdns1110 - update to 9.11.22-3.74.1
bind-utils - addressed in versions 9.11.22-3.74.1, 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1, 9.18.50-150600.3.32.1, 9.20.26-150700.3.29.1
libisccc161 - update to 9.11.22-3.74.1
libisc1107-debuginfo - update to 9.11.22-3.74.1
bind-devel - addressed in versions 9.11.22-3.74.1, 9.16.6-150300.22.62.1
bind - addressed in versions 9.11.36-16.0.1, 9.20.26-1
python3-bind - update to 9.11.36-16.0.1
bind-license - addressed in versions 9.11.36-16.0.1, 9.20.26-1
bind-utils - addressed in versions 9.11.36-16.0.1, 9.20.26-1
bind-sdb-chroot - update to 9.11.36-16.0.1
bind-sdb - update to 9.11.36-16.0.1
bind-pkcs11-utils - update to 9.11.36-16.0.1
bind-pkcs11-libs - update to 9.11.36-16.0.1
bind-chroot - addressed in versions 9.11.36-16.0.1, 9.20.26-1
bind-devel - addressed in versions 9.11.36-16.0.1, 9.20.26-1
bind-export-devel - update to 9.11.36-16.0.1
bind-export-libs - update to 9.11.36-16.0.1
bind-libs - addressed in versions 9.11.36-16.0.1, 9.20.26-1
bind-libs-lite - update to 9.11.36-16.0.1
bind-lite-devel - update to 9.11.36-16.0.1
bind-pkcs11 - update to 9.11.36-16.0.1
bind-pkcs11-devel - update to 9.11.36-16.0.1
libirs1601-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libisc1606 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
python3-bind - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1, 9.16.50-150400.5.65.1, 9.16.50-150500.8.41.1
libisccfg1600-64bit - update to 9.16.6-150000.12.91.1
libirs1601-64bit - update to 9.16.6-150000.12.91.1
libisccc1600-64bit - update to 9.16.6-150000.12.91.1
libdns1605-64bit - update to 9.16.6-150000.12.91.1
libisc1606-64bit - update to 9.16.6-150000.12.91.1
libbind9-1600-64bit - update to 9.16.6-150000.12.91.1
libdns1605-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libisccc1600-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libbind9-1600-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libisc1606-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libisccc1600 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libisccfg1600 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libdns1605 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libirs1601 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libisccfg1600-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libbind9-1600 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libns1604-debuginfo - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libns1604 - addressed in versions 9.16.6-150000.12.91.1, 9.16.6-150300.22.62.1
libirs-devel - update to 9.16.6-150300.22.62.1
bind9.16-license - update to 9.16.23-0.22
python3-bind9.16 - update to 9.16.23-0.22
bind9.16 - update to 9.16.23-0.22
bind9.16-chroot - update to 9.16.23-0.22
bind9.16-devel - update to 9.16.23-0.22
bind9.16-dnssec-utils - update to 9.16.23-0.22
bind9.16-libs - update to 9.16.23-0.22
bind9.16-utils - update to 9.16.23-0.22
bind9.16-doc - update to 9.16.23-0.22
bind9.16 (Red Hat package) - update to 9.16.23-0.22.el8_10.12
bind-license - addressed in versions 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-dnssec-utils - addressed in versions 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-dnssec-doc - addressed in versions 9.16.23-31, 9.18.21-11, 9.20.21-4
bind-pkcs11-utils - update to 9.16.23-31
bind-pkcs11-libs - update to 9.16.23-31
bind9 (Ubuntu package) - addressed in versions 1:9.18.39-0ubuntu0.22.04.5, 1:9.18.39-0ubuntu0.24.04.6, 1:9.20.24-1ubuntu0.2
bind - addressed in versions 9.18.50-2.fc43, 9.18.50-2.fc44, 9.18.50-34.fc45
bind-doc - update to 9.20.26-1
bind-dnssec-utils - update to 9.20.26-1
bind-dnssec-doc - update to 9.20.26-1
bind9 (Debian package) - update to 1:9.20.26-1~deb13u1

• https://kb.isc.org/docs/cve-2026-11721-cache-poisoning-label-count-discrepancy-rrsig-wildcards
• https://kb.isc.org/docs/cve-2026-11721

• Multiple vulnerabilities in ISC BIND
• Debian update for bind9
• SUSE update for bind
• SUSE update for bind
• SUSE update for bind
• SUSE update for bind
• SUSE update for bind
• SUSE update for bind
• openEuler 24.03 LTS SP1 update for bind
• openEuler 24.03 LTS SP4 update for bind
• openEuler 24.03 LTS SP3 update for bind
• SUSE update for bind
• Anolis OS update for bind
• Red Hat Enterprise Linux 8 update for bind9.16
• Red Hat Enterprise Linux 9 update for bind
• Red Hat Enterprise Linux 8 update for bind
• openEuler 22.03 LTS SP4 update for bind
• openEuler 20.03 LTS SP4 update for bind
• Anolis OS update for bind
• Anolis OS update for bind9.16
• Ubuntu update for bind9
• Red Hat Enterprise Linux 9 update for bind
• Multiple vulnerabilities in Red Hat OpenShift Container Platform 4.22
• Fedora 45 update for bind
• Fedora 44 update for bind
• Fedora 43 update for bind
• Red Hat Enterprise Linux 7 Extended Lifecycle Support update for bind