CVE-2026-18321 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in ntpsec
A local attacker can crash the NTPsec daemon via a buffer overflow in the Zyfer refclock driver, requiring that specific hardware driver to be enabled.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-18321?
CVE-2026-18321 is a medium-severity memory corruption vulnerability in ntpsec, published on 31 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Buffer overflow in NTPsec's Zyfer refclock allows local attacker to crash ntpd
Weakness: CWE-120
Which versions are affected by CVE-2026-18321?
Linux distribution packages (1)
ntpsec openSUSE:Tumbleweed | All versions | 1.2.5-1.1 |
How do I fix CVE-2026-18321?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-18321 being exploited?
There is no known exploitation of CVE-2026-18321 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-18321, GHSA-6978-pcpc-2c45, MGASA-2026-0430, MINI-w8x7-hxqv-7qw4, UBUNTU-CVE-2026-18321, openSUSE-SU-2026:11417-1.