Memory bloat via DNSSEC subdom attack on ISC BIND 9 (9.18.50/9.20.24/9.21.23)
CVE-2026-11622 Published on July 22, 2026
Potential memory usage beyond configured limits
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.
Vulnerability Analysis
CVE-2026-11622 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
Allocation of Resources Without Limits or Throttling
The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.
Products Associated with CVE-2026-11622
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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.