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Vulnerability record · CVE-2026-5946 · published 20 May 2026

CVE-2026-5946: Isc bind improper input validation vulnerability

Isc · Bind

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.

7.5 CVSS 3.1 High EPSS 1.7% · top 23.8% CWE-20 · Improper input validationCWE-125 · Out-of-bounds read
7.5CVSS 3.1 base score
1.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
18References
17 Sep 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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://kb.isc.org/docs/cve-2026-5946 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:20334
https://access.redhat.com/errata/RHSA-2026:23360
https://access.redhat.com/errata/RHSA-2026:24338
https://access.redhat.com/errata/RHSA-2026:24339
https://access.redhat.com/errata/RHSA-2026:24367
https://access.redhat.com/errata/RHSA-2026:24368
https://access.redhat.com/errata/RHSA-2026:55441
https://access.redhat.com/errata/RHSA-2026:57189
https://access.redhat.com/errata/RHSA-2026:60383
https://access.redhat.com/errata/RHSA-2026:62549
https://access.redhat.com/errata/RHSA-2026:65851
https://access.redhat.com/security/cve/CVE-2026-5946
https://bugzilla.redhat.com/show_bug.cgi?id=2479771
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5946.json

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-5946), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.