BIND 9 DNS Crash: NSEC/NSEC3 RRSIG Mismatch (v9.11-9.21)
CVE-2026-13204 Published on July 22, 2026
Unexpected exit in certain situations with NSEC and NSEC3 both present
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, then BIND may exit unexpectedly with an assertion while validating this proof.
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.
Vulnerability Analysis
CVE-2026-13204 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is an assertion failure Vulnerability?
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
CVE-2026-13204 has been classified to as an assertion failure vulnerability or weakness.
Products Associated with CVE-2026-13204
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Affected Versions
ISC BIND 9:- Version 9.11.0, <= 9.18.50 is affected.
- Version 9.20.0, <= 9.20.24 is affected.
- Version 9.21.0, <= 9.21.23 is affected.
- Version 9.11.3-S1, <= 9.18.50-S1 is affected.
- Version 9.20.9-S1, <= 9.20.24-S1 is affected.