CVE-2026-11605: ISC BIND 9

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

The issue is a resource exhaustion vulnerability associated with DNSSEC validation. BIND always validates all RRSIG records in an answer, even if they are not strictly needed. A query to an authoritative server/zone which returns many valid but superfluous RRSIG records causes the validator to waste disproportionate CPU time. This issue affects BIND 9 versions 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, and 9.20.9-S1 through 9.20.24-S1.

Affected products

• ISC BIND 9: from 9.20.0, up to and including 9.20.24; from 9.21.0, up to and including 9.21.23; from 9.20.9-S1, up to and including 9.20.24-S1

Published 2026-07-22. Last modified 2026-07-22.