CVE-2023-4012 Incomplete Internal State Distinction in ntpsec

High 7.5 Published 7 Aug 2023 Updated 22 Jun 2026

An attacker can crash the NTPsec server by sending NTS-enabled requests to a non-NTS server, causing a denial of service.

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

What is CVE-2023-4012?

CVE-2023-4012 is a high-severity denial of service vulnerability in ntpsec, published on 7 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

ntpd will crash if the server is not NTS-enabled (no certificate) and it receives an NTS-enabled client request (mode 3).

Weakness: CWE-372

Which versions are affected by CVE-2023-4012?

It affects 1 product.

Products include Ntpsec Ntpsec.

How do I fix CVE-2023-4012?

Apply the vendor's patch.

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-2023-4012 being exploited?

There is no known exploitation of CVE-2023-4012 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2023-4012, DSA-5466-1, GHSA-777h-w3h9-x4qv, UBUNTU-CVE-2023-4012, openSUSE-SU-2024:13463-1.