CVE-2026-19666: Use-after-free in query_addnoqnameproof() via the DNS64 filter64 path

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-16 · updated 2026-10-26
Weakness: CWE-416

Description

On a resolver configured to use ``dns64``, if an applicable answer from the authoritative server is malformed in a specific way, the resolver `named` process will exit unexpectedly. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

Affected products

ISC BIND: from 9.11.0 through 9.18.50; from 9.20.0 through 9.20.27; from 9.21.0 through 9.21.25; from 9.11.3-S1 through 9.18.50-S1; from 9.20.9-S1 through 9.20.27-S1

References

https://downloads.isc.org/isc/bind9/9.20.29
https://downloads.isc.org/isc/bind9/9.21.26
https://kb.isc.org/docs/cve-2026-19666

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