CVE-2026-5946: ISC BIND 9 · Improper Input Validation
Affects ISC BIND 9Source CVE Database V5
Not known to be exploited · CVSS 7.5 High · fixed in 9.21.22 : patch ISC BIND 9 soon.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 1.9% chance of exploitation in 30 days – higher than 80% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 9.21.22, 9.20.23, 9.18.49 +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 20 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade isc/bind9 to 9.21.22, 9.20.23, 9.18.49 or 9.16.51.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| ISCBIND 9 | Affected
| Fixed in– |
Iscisc/bind9pkg:deb/isc/bind9Other threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and has been released by ISC and vendors such as Red Hat. Users should apply the official security updates to affected BIND 9 versions as soon as possible. Vendor advisories indicate that no effective mitigations other than patching currently meet criteria for ease of use and applicability. Red Hat customers should follow the update instructions in their advisories. Monitoring for unusual DNS message classes and restricting access to DNS services may reduce exposure but are not formal mitigations.
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.
References
- kb.isc.org/docs/cve-2026-5946 (opens in a new tab)
- downloads.isc.org/isc/bind9/9.18.49 (opens in a new tab)
- downloads.isc.org/isc/bind9/9.20.23 (opens in a new tab)
- downloads.isc.org/isc/bind9/9.21.22 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-5946 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2479771 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5946.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:24338 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:24339 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:23360 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:24367 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:24368 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:20334 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:55441 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:57189 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:60383 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62549 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65851 (opens in a new tab)