CVE-2026-5946

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 v3 vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses (CWE)

CWE-20, CWE-125, CWE-617, CWE-754, CWE-843

Threats tracking this CVE

• BIND 9 Multi-CVE Disclosure (May 2026) — Heap UAF in DoH (CVE-2026-3593), SIG(0) UAF (CVE-2026-5947), Resolver Resend Loop DoS (CVE-2026-5950), CLASS!=IN Assertion DoS (CVE-2026-5946), Glue Amplification (CVE-2026-3592), GSS-API TKEY Memory Exhaustion (CVE-2026-3039) — HIGH

References

• https://kb.isc.org/docs/cve-2026-5946
• https://downloads.isc.org/isc/bind9/9.18.49
• https://downloads.isc.org/isc/bind9/9.20.23
• https://downloads.isc.org/isc/bind9/9.21.22

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