BIND 9 DoS via Unbounded DNS Message Processing (9.11.0-9.21.26)
CVE-2026-19630 Published on October 21, 2026
Amplified resource exhaustion in inbound message processing
In a BIND resolver, inbound DNS protocol messages with a particular structure will result in additional processing, with no limit imposed by BIND. A DNS message with a maliciously large number of such structures will cause BIND to consume disproportionate amounts of CPU time and memory during processing.
This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.
Vulnerability Analysis
CVE-2026-19630 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
Inefficient Algorithmic Complexity
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
Products Associated with CVE-2026-19630
Want to know whenever a new CVE is published for ISC BIND? stack.watch will email you.
Affected Versions
ISC BIND 9:- Version 9.11.0, <= 9.18.50 is affected.
- Version 9.20.0, <= 9.20.29 is affected.
- Version 9.21.0, <= 9.21.26 is affected.
- Version 9.11.3-S1, <= 9.18.50-S1 is affected.
- Version 9.20.9-S1, <= 9.20.29-S1 is affected.