Use After Free in Isc Bind 9
CVE-2026-19662
An attacker may be able to cause a `named` resolver to abort. The attack requires inducing the victim resolver to send multiple queries for a DNSSEC-signed zone hosted by an authoritative server under the control of the attacker. If the auth responds with a particular sequence of crafted answers, and those answers arrive in a particular order with particular timing, the `named` resolver will encounter a use-after-free bug, and abort. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 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 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/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)
Frequently asked questions
- What is CVE-2026-19662?
- CVE-2026-19662 is a medium-severity vulnerability in Isc Bind 9, classified under Use After Free. CVSS score: 5.9/10. Published 2026-09-16.
- How severe is CVE-2026-19662?
- Medium severity. CVSS v3 base score is 5.9 out of 10.