CVE-2026-13204 ISC CVE debrief

Who should care

BIND users and administrators should review their configurations and update to a patched version if vulnerable. This includes reviewing the configurations of 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. Security teams and operators managing DNS infrastructure should prioritize patching.

Technical summary

BIND may exit unexpectedly with an assertion while validating proof if a provably insecure domain is covered by both an NSEC and NSEC3 record at the parent, and there exist an RRSIG for only one of these types. 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. The vulnerability is related to DNSSEC validation and can cause service disruption.

Defensive priority

High priority due to potential for service disruption and impact on DNS infrastructure.

Recommended defensive actions

• Review BIND configurations and versions
• Update to a patched version if vulnerable
• Monitor for potential exploitation attempts
• Verify BIND configurations for compliance
• Perform vulnerability scanning
• Implement compensating controls
• Track exceptions and retest remediated assets

Evidence notes

Evidence is limited; further investigation is recommended. The CVE record was published on 2026-07-22T15:16:52.080Z and has not been modified since then. BIND users and administrators should verify their configurations and review potential impacts. Defensive verification tasks are necessary due to limited source detail.

Official resources