Use After Free in Isc Bind 9
CVE-2026-19666
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.
Vulnerability class: Use-After-Free
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
Weakness classification (CWE)
References
- security-officer@isc.org (vendor-advisory)
- security-officer@isc.org (patch)
- security-officer@isc.org (patch)
Frequently asked questions
- What is CVE-2026-19666?
- CVE-2026-19666 is a high-severity vulnerability in Isc Bind 9, classified under Use After Free. CVSS score: 7.5/10. Published 2026-09-16.
- How severe is CVE-2026-19666?
- High severity. CVSS v3 base score is 7.5 out of 10.