CVE-2026-11721: It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels

Routine

HIGH 7.5REMOTE

CVE-2026-11721 is a high-severity flaw (CVSS 7.5) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 versi

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-1284
Published	2026-07-22
Last modified	2026-10-24

Publisher (CNA): Internet Systems Consortium (ISC)

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-07-22 15:16 UTCPublished CVE record published
2026-10-24 18:10 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · uv · FIXED · 0.13.5-2.fc46 · FEDORA-2026-0a45cde16b · source

sudo dnf upgrade --advisory=FEDORA-2026-0a45cde16b

Fedora ELN · oo7 · FIXED · 0.7.0~beta-3.eln159 · FEDORA-2026-f348262964 · source

sudo dnf upgrade --advisory=FEDORA-2026-f348262964

Ubuntu 22.04 · bind9 · FIXED · 1:9.18.39-0ubuntu0.22.04.5

sudo apt update && sudo apt install --only-upgrade bind9 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' bind9)" ge "1:9.18.39-0ubuntu0.22.04.5" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · bind9 · FIXED · 1:9.18.39-0ubuntu0.24.04.6

sudo apt update && sudo apt install --only-upgrade bind9 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' bind9)" ge "1:9.18.39-0ubuntu0.24.04.6" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · bind9 · FIXED · 1:9.18.30-0ubuntu0.20.04.2+esm3

sudo apt update && sudo apt install --only-upgrade bind9 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' bind9)" ge "1:9.18.30-0ubuntu0.20.04.2+esm3" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · isc-dhcp · NOT AFFECTED

Ubuntu 22.04 · isc-dhcp · NOT AFFECTED

Debian 12 · bind9 · FIXED · 1:9.18.49-1~deb12u2

sudo apt update && sudo apt install --only-upgrade bind9 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' bind9)" ge "1:9.18.49-1~deb12u2" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · bind9 · FIXED · 1:9.20.26-1~deb13u1

sudo apt update && sudo apt install --only-upgrade bind9 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' bind9)" ge "1:9.20.26-1~deb13u1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · bind · FIXED · bind-9.18.33-15.el10_2.10

sudo dnf upgrade --advisory=RHSA-2026:55437 rpm -q bind

RHEL 7 Extended Lifecycle Support · bind · FIXED · bind-9.11.4-26.P2.el7_9.21

sudo dnf upgrade --advisory=RHSA-2026:60383 rpm -q bind

RHEL 8 · bind9.16 · FIXED · bind9.16-9.16.23-0.22.el8_10.12

sudo dnf upgrade --advisory=RHSA-2026:54509 rpm -q bind9.16

RHEL 8 · bind · FIXED · bind-9.11.36-16.el8_10.14

sudo dnf upgrade --advisory=RHSA-2026:54654 rpm -q bind

RHEL 8.6 Advanced Mission Critical Update Support · bind9.16 · FIXED · bind9.16-9.16.23-0.7.el8_6.11

sudo dnf upgrade --advisory=RHSA-2026:80501 rpm -q bind9.16

Alpine 3.22 · bind · FIXED · bind-9.20.26-r0

apk add --upgrade bind apk info -v bind

Alpine 3.23 · bind · FIXED · bind-9.20.26-r0

apk add --upgrade bind apk info -v bind

Alpine 3.24 · bind · FIXED · bind-9.20.26-r0

apk add --upgrade bind apk info -v bind

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-2040 · source

sudo dnf update --advisory=ALAS2023-2026-2040

Amazon Linux 2 · see advisory · FIXED · ALAS2-2026-3854 · source

sudo yum update --advisory=ALAS2-2026-3854

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-11721?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-11721 being exploited?

CVE-2026-11721 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-11721 affect?

CVE-2026-11721 affects affected software. Severity is high (CVSS 7.5). 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

How urgent is CVE-2026-11721?

Priority 39/100. High severity; Remotely exploitable, no login, no user action

Software pages

BIND DNS vulnerabilities

References

← Back to latest CVEs