CVE-2023-26249 Denial of service in n/a

High 7.5 Published 21 Feb 2023 Updated 14 Mar 2025

Attackers can cause denial of service in Knot Resolver by triggering excessive TCP connection attempts through malicious DNS responses.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2023-26249?

CVE-2023-26249 is a high-severity denial of service vulnerability in n/a, published on 21 Feb 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification attacks and potentially causing a denial of service. Specifically, a single client query may lead to a hundred TCP connection attempts if a DNS server closes connections without providing a response.

Weakness: CWE-770

Which versions are affected by CVE-2023-26249?

It affects 1 product.

Products include Nic Knot Resolver.

How do I fix CVE-2023-26249?

Upgrade to a fixed version.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-26249 being exploited?

There is no known exploitation of CVE-2023-26249 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2023-26249, GHSA-38wr-pjxc-vgf7, UBUNTU-CVE-2023-26249.