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

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.

Published: 2026-05-20 Last update: 2026-05-21 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-5946 is rated Moderate Risk (43.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.49%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-5946

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.06% 0.49% +0.44%
2 2026-05-26 0.03% 0.06% +0.03%
3 2026-05-21 — 0.03% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-5946

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-5946

GitHub Security Advisory for CVE-2026-5946

GHSA-cqgq-ff3f-rj7r · Severity: high — Multiple flaws have been identified in `named` related to the handling of DNS messages whose...

OS Trackers for CVE-2026-5946

vendor priority summary link
debian not yet assigned CVE-2026-5946 not yet assigned priority: Debian including 1 source packages (bind9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2026-5946
redhat high — https://access.redhat.com/security/cve/CVE-2026-5946
suse high — https://www.suse.com/security/cve/CVE-2026-5946/
ubuntu medium CVE-2026-5946 medium priority: Ubuntu including 3 source packages (bind9, bind9-libs, isc-dhcp), 24 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): needs-triage 12, released 5, not-affected 4, DNE 3. https://ubuntu.com/security/CVE-2026-5946

Affected software / configurations for CVE-2026-5946

Vendor Product Version Raw CPE
isc bind >= 9.11.0, <= 9.16.50 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.18.0, < 9.18.49 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.20.0, < 9.20.23 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.21.0, < 9.21.22 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*

References for CVE-2026-5946

cvelogic Threat Intelligence