CVE-2025-40776: ISC BIND 9

High severity, CVSS 8.6. EPSS: 0.2% chance of exploitation in the next 30 days.

A `named` caching resolver that is configured to send ECS (EDNS Client Subnet) options may be vulnerable to a cache-poisoning attack. This issue affects BIND 9 versions 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.37-S1, and 9.20.9-S1 through 9.20.10-S1.

Affected products

• ISC BIND 9: from 9.11.3-S1, up to and including 9.16.50-S1; from 9.18.11-S1, up to and including 9.18.37-S1; from 9.20.9-S1, up to and including 9.20.10-S1

Published 2025-07-16. Last modified 2026-06-17.