CVE-2026-18103 Dhcp-server: dhcp-server: persistent denial of service due to buffer overflow via omapi
Remote attackers can cause persistent denial of service in the DHCP server by sending crafted OMAPI requests with overly long MAC addresses.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18103?
CVE-2026-18103 is a medium-severity memory corruption vulnerability in Red Hat Enterprise Linux 6, published on 4 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
A flaw was found in dhcp-server. A remote attacker with network access to the OMAPI (Open Management Application Programming Interface) port, especially if not secured with TSIG (Transaction Signature) key authentication, could send a specially crafted lease creation request. This request, containing an overly long InfiniBand MAC address, triggers a buffer overflow in the `print_hw_addr()` function. Successful exploitation leads to a persistent denial of service (DoS), causing the `dhcpd` service to crash and preventing it from restarting without manual intervention.
Weakness: CWE-120
Which versions are affected by CVE-2026-18103?
How do I fix CVE-2026-18103?
No fix has been published for CVE-2026-18103 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-18103 being exploited?
There is no known exploitation of CVE-2026-18103 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-18103, GHSA-wq4j-5vp3-jcrx, UBUNTU-CVE-2026-18103.