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Fencer Vulns
medium 4.9

CVE-2026-18103 json

Dhcp-server: dhcp-server: persistent denial of service due to buffer overflow via omapi

published 2026-08-04 3 mo ago modified 2026-11-06 2 d ago also EUVD-2026-52999

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 53%
public exploits
0
none known

Summary

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.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-18103 updated cvss 4.9

dhcp-server: dhcp-server: Persistent denial of service due to buffer overflow via OMAPI

  • Red Hat Enterprise Linux 6 dhcp, dhclient, dhcp-common Red Hat Enterprise Linux 7 dhcp, dhclient, dhcp-libs, dhcp-common Red Hat Enterprise Linux 8 dhcp, dhcp-libs, dhcp-relay, dhcp-client, dhcp-common, dhcp-server
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 9 dhcp, dhcp-relay, dhcp-client, dhcp-common, dhcp-server
    affected: workaround, no fix available

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.71% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.