Vulnerability in Isc Bind 9
CVE-2026-12617
The issue is unexpected program termination based on ordering and/or specific content in responses to queries for CNAME or DNAME, and A records. Specifically, if a client queries for a DNAME and A record below the DNAME to the resolver, and the authoritative server responds positively to the A query but delays the DNAME response and later responds negatively, `named` may quit unexpectedly. Or, if a client queries for a CNAME and A record for the same name to the resolver, and the authoritative server responds positively to the A query but delays the CNAME response and later responds with a self-referential CNAME, the same failure may occur. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.
EPSS: 0.005 (41.0th percentile) — read the EPSS interpretation.
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
- Isc Bind 9 — versions 9.18.0, 9.20.0, 9.18.11-S1
Weakness classification (CWE)
References
- security-officer@isc.org (vendor-advisory)
- security-officer@isc.org (patch)
Frequently asked questions
- What is CVE-2026-12617?
- CVE-2026-12617 is a high-severity vulnerability in Isc Bind 9, classified under Reachable Assertion. CVSS score: 7.5/10. Published 2026-07-22.
- How severe is CVE-2026-12617?
- High severity. CVSS v3 base score is 7.5 out of 10.