CVE-2026-11331: ISC BIND 9

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

An attacker who knows (or guesses) that a resolver uses RPZ with wildcard CNAME policies can craft query names long enough to trigger a NAMETOOLONG error condition during RPZ processing. This is not handled correctly and may lead to defeating the RPZ rule. It also may lead to an unexpected exit of the BIND 9 software. This issue affects BIND 9 versions 9.16.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.16.8-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

Affected products

• ISC BIND 9: from 9.16.0, 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 9.16.8-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.