USN-8037-1: DNSdist vulnerabilities

Publication date

12 February 2026

Overview

Several security issues were fixed in dnsdist.


Packages

  • dnsdist - A highly DNS-, DoS- and abuse-aware loadbalancer

Details

It was discovered that HTTP/2, which is used/vendored by DNSdist, did not
properly account for resources when handling client-triggered stream
resets. An attacker could possibly use this issue to cause a
denial of service. (CVE-2025-8671)

It was discovered that DNSdist did not properly manage memory limits when
handling an unlimited number of queries on a single TCP connection. An
attacker could possibly use this issue to cause a denial of service.
(CVE-2025-30193)

It was discovered that DNSdist, when configured with the nghttp2 library,
did not correctly process certain DNS over HTTPS queries. An attacker
could possibly use this cause a denial of service. (CVE-2025-30187)

It was discovered that HTTP/2, which is used/vendored by DNSdist, did not
properly account for resources when handling client-triggered stream
resets. An attacker could possibly use this issue to cause a
denial of service. (CVE-2025-8671)

It was discovered that DNSdist did not properly manage memory limits when
handling an unlimited number of queries on a single TCP connection. An
attacker could possibly use this issue to cause a denial of service.
(CVE-2025-30193)

It was discovered that DNSdist, when configured with the nghttp2 library,
did not correctly process certain DNS over HTTPS queries. An attacker
could possibly use this cause a denial of service. (CVE-2025-30187)

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
25.10 questing dnsdist –  1.9.10-1ubuntu0.1
24.04 LTS noble dnsdist –  1.8.3-2ubuntu0.1~esm1  
22.04 LTS jammy dnsdist –  1.6.1-1ubuntu0.1~esm2  

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