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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | isc-dhcp | No fix yet | — |
| Debian 12 | isc-dhcp | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | isc-dhcp | No fix yet | — |
| Ubuntu 24.04 LTS | isc-dhcp | No fix yet | — |
| Ubuntu 22.04 LTS | isc-dhcp | No fix yet | — |
| Ubuntu 20.04 LTS | isc-dhcp | No fix yet | — |
| Ubuntu 18.04 LTS | isc-dhcp | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | isc-dhcp | No fix yet | — |
| Ubuntu Pro 14.04 LTS | isc-dhcp | No fix yet | — |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 9 | dhcp-relay +3 | 2:4.4.2-22.b1.el9.rocky.0.1 | RLSA-2026:97486 |
Advisories 2
- RLSA-2026:97486 Low: dhcp security, bug fix, and enhancement update Rocky Linux Security Advisories · Nov 13, 2026
- WID-SEC-2026-4456 Red Hat Enterprise Linux (dhcp-server): Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Nov 10, 2026
References
- RHSA-2026:97486 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-18103 vdb-entry
- RHBZ#2508081 issue-tracking