Vulnerability · Published May 20, 2026 · Assigned by isc

CVE-2026-5946Invalid handling of CLASS != IN

High 7.5

In plain English

A high-severity improper input validation in BIND 9 from ISC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.9% (higher than 80% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)1.9%top 19.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Multiple flaws have been identified in `named` related to the handling of DNS messages whose CLASS is not Internet (`IN`) — for example, `CHAOS` or `HESIOD`, or DNS messages that specify meta-classes (`ANY` or `NONE`) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (`UPDATE`), zone change notifications (`NOTIFY`), or processing of `IN`-specific record types in non-`IN` data — can cause assertion failures in `named`. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
AlmaLinux:10	bind	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:8	bind	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	bind	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:10	bind-chroot	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:8	bind-chroot	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	bind-chroot	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:10	bind-devel	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:8	bind-devel	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	bind-devel	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:9	bind-dnssec-doc	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:10	bind-dnssec-utils	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:9	bind-dnssec-utils	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:10	bind-doc	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:9	bind-doc	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:8	bind-export-devel	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-export-libs	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:10	bind-libs	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:8	bind-libs	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	bind-libs	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:8	bind-libs-lite	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:10	bind-license	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:8	bind-license	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	bind-license	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:8	bind-lite-devel	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-pkcs11	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-pkcs11-devel	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-pkcs11-libs	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-pkcs11-utils	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-sdb	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:8	bind-sdb-chroot	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:10	bind-utils	32:9.18.33-15.el10_2.2	ALSA-2026:24338
AlmaLinux:8	bind-utils	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	bind-utils	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:8	bind9.16	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-chroot	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-devel	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-dnssec-utils	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-doc	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-libs	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-license	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:8	bind9.16-utils	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
AlmaLinux:9	bind9.18	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:9	bind9.18-chroot	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:9	bind9.18-devel	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:9	bind9.18-dnssec-utils	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:9	bind9.18-doc	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:9	bind9.18-libs	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:9	bind9.18-utils	32:9.18.29-14.el9_8.2	ALSA-2026:24368
AlmaLinux:8	python3-bind	32:9.11.36-16.el8_10.8	ALSA-2026:24339
AlmaLinux:9	python3-bind	32:9.16.23-40.el9_8.2	ALSA-2026:24367
AlmaLinux:8	python3-bind9.16	32:9.16.23-0.22.el8_10.6	ALSA-2026:23360
Alpine:v3.20	bind	9.18.49-r0	ALPINE-CVE-2026-5946
Alpine:v3.21	bind	9.18.49-r0	ALPINE-CVE-2026-5946
Alpine:v3.22	bind	9.20.23-r0	ALPINE-CVE-2026-5946
Alpine:v3.23	bind	9.20.23-r0	ALPINE-CVE-2026-5946
Alpine:v3.24	bind	9.20.23-r0	ALPINE-CVE-2026-5946
Debian:12	bind9	1:9.18.49-1~deb12u2	DEBIAN-CVE-2026-5946
Debian:13	bind9	1:9.20.23-1~deb13u1	DEBIAN-CVE-2026-5946
Debian:14	bind9	1:9.20.23-1	DEBIAN-CVE-2026-5946
Rocky Linux:10	bind	2:9.18.33-15.el10_2.2	RLSA-2026:24338
Rocky Linux:8	bind	2:9.11.36-16.el8_10.8	RLSA-2026:24339
Rocky Linux:9	bind	2:9.16.23-40.el9_8.2	RLSA-2026:24367
Rocky Linux:8	bind9.16	2:9.16.23-0.22.el8_10.6	RLSA-2026:23360
Rocky Linux:9	bind9.18	2:9.18.29-14.el9_8.2	RLSA-2026:24368
Ubuntu:22.04:LTS	bind9	1:9.18.39-0ubuntu0.22.04.4	UBUNTU-CVE-2026-5946
Ubuntu:24.04:LTS	bind9	1:9.18.39-0ubuntu0.24.04.5	UBUNTU-CVE-2026-5946
Ubuntu:25.10	bind9	1:9.20.11-1ubuntu2.4	UBUNTU-CVE-2026-5946
Ubuntu:26.04:LTS	bind9	1:9.20.18-1ubuntu2.1	UBUNTU-CVE-2026-5946
Ubuntu:22.04:LTS	bind9-libs	no fix listed	UBUNTU-CVE-2026-5946

Affected products (as reported)

Vendor	Product	Versions
ISC	BIND 9	9.11.0 – through 9.16.509.18.0 – through 9.18.489.20.0 – through 9.20.229.21.0 – through 9.21.219.11.3-S1 – through 9.16.50-S19.18.11-S1 – through 9.18.48-S19.20.9-S1 – through 9.20.22-S1

Weakness: CWE-20, CWE-125, CWE-617, CWE-754, CWE-843, CWE-1287 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

CVE-2026-5946 vendor-advisory
https://downloads.isc.org/isc/bind9/9.18.49 patch
https://downloads.isc.org/isc/bind9/9.20.23 patch
https://downloads.isc.org/isc/bind9/9.21.22 patch
https://access.redhat.com/security/cve/CVE-2026-5946 vdb-entry, x_refsource_REDHAT
RHBZ#2479771 issue-tracking, x_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5946.json x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:60383 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:62549 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:65851 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:24338 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:24339 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:23360 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:57189 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:55441 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:24367 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:24368 vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:20334 vendor-advisory, x_refsource_REDHAT