CVE-2026-11622: ISC BIND 9

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

A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the `max-cache-size` parameter. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

Affected products

• ISC BIND 9: from 9.11.0, up to and including 9.18.50; from 9.20.0, up to and including 9.20.24; from 9.21.0, up to and including 9.21.23; from 9.11.3-S1, up to and including 9.18.50-S1; from 9.20.9-S1, up to and including 9.20.24-S1

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