{"id":"UBUNTU-CVE-2026-18103","details":"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.","modified":"2026-08-19T11:01:27Z","published":"2026-08-05T00:16:00Z","upstream":["CVE-2026-18103"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-18103"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-18103"}],"affected":[{"package":{"name":"isc-dhcp","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/isc-dhcp?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.2.4-7ubuntu8","4.2.4-7ubuntu9","4.2.4-7ubuntu10","4.2.4-7ubuntu11","4.2.4-7ubuntu12","4.2.4-7ubuntu12.1","4.2.4-7ubuntu12.2","4.2.4-7ubuntu12.3","4.2.4-7ubuntu12.4","4.2.4-7ubuntu12.5","4.2.4-7ubuntu12.6","4.2.4-7ubuntu12.7","4.2.4-7ubuntu12.8","4.2.4-7ubuntu12.9","4.2.4-7ubuntu12.10","4.2.4-7ubuntu12.12","4.2.4-7ubuntu12.13","4.2.4-7ubuntu12.13+esm1","4.2.4-7ubuntu12.13+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"isc-dhcp-client","binary_version":"4.2.4-7ubuntu12.13+esm2"},{"binary_name":"isc-dhcp-client-noddns","binary_version":"4.2.4-7ubuntu12.13+esm2"},{"binary_version":"4.2.4-7ubuntu12.13+esm2","binary_name":"isc-dhcp-common"},{"binary_name":"isc-dhcp-relay","binary_version":"4.2.4-7ubuntu12.13+esm2"},{"binary_name":"isc-dhcp-server","binary_version":"4.2.4-7ubuntu12.13+esm2"},{"binary_version":"4.2.4-7ubuntu12.13+esm2","binary_name":"isc-dhcp-server-ldap"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"}},{"package":{"name":"isc-dhcp","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/isc-dhcp?arch=source&distro=esm-infra%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.3.1-5ubuntu3","4.3.1-5ubuntu4","4.3.1-5ubuntu5","4.3.3-5ubuntu1","4.3.3-5ubuntu2","4.3.3-5ubuntu4","4.3.3-5ubuntu5","4.3.3-5ubuntu7","4.3.3-5ubuntu8","4.3.3-5ubuntu9","4.3.3-5ubuntu10","4.3.3-5ubuntu11","4.3.3-5ubuntu12","4.3.3-5ubuntu12.1","4.3.3-5ubuntu12.3","4.3.3-5ubuntu12.4","4.3.3-5ubuntu12.6","4.3.3-5ubuntu12.7","4.3.3-5ubuntu12.9","4.3.3-5ubuntu12.10","4.3.3-5ubuntu12.10+esm1","4.3.3-5ubuntu12.10+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"isc-dhcp-client","binary_version":"4.3.3-5ubuntu12.10+esm2"},{"binary_version":"4.3.3-5ubuntu12.10+esm2","binary_name":"isc-dhcp-client-ddns"},{"binary_version":"4.3.3-5ubuntu12.10+esm2","binary_name":"isc-dhcp-common"},{"binary_version":"4.3.3-5ubuntu12.10+esm2","binary_name":"isc-dhcp-relay"},{"binary_name":"isc-dhcp-server","binary_version":"4.3.3-5ubuntu12.10+esm2"},{"binary_name":"isc-dhcp-server-ldap","binary_version":"4.3.3-5ubuntu12.10+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"}},{"package":{"name":"isc-dhcp","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/isc-dhcp?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.3.5-3ubuntu2","4.3.5-3ubuntu3","4.3.5-3ubuntu4","4.3.5-3ubuntu5","4.3.5-3ubuntu6","4.3.5-3ubuntu7","4.3.5-3ubuntu7.1","4.3.5-3ubuntu7.2","4.3.5-3ubuntu7.3","4.3.5-3ubuntu7.4"],"ecosystem_specific":{"binaries":[{"binary_name":"isc-dhcp-client","binary_version":"4.3.5-3ubuntu7.4"},{"binary_name":"isc-dhcp-client-ddns","binary_version":"4.3.5-3ubuntu7.4"},{"binary_name":"isc-dhcp-common","binary_version":"4.3.5-3ubuntu7.4"},{"binary_name":"isc-dhcp-relay","binary_version":"4.3.5-3ubuntu7.4"},{"binary_name":"isc-dhcp-server","binary_version":"4.3.5-3ubuntu7.4"},{"binary_version":"4.3.5-3ubuntu7.4","binary_name":"isc-dhcp-server-ldap"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"}},{"package":{"name":"isc-dhcp","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/isc-dhcp?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.4.1-2ubuntu5","4.4.1-2ubuntu6","4.4.1-2.1ubuntu1","4.4.1-2.1ubuntu2","4.4.1-2.1ubuntu3","4.4.1-2.1ubuntu4","4.4.1-2.1ubuntu5","4.4.1-2.1ubuntu5.20.04.1","4.4.1-2.1ubuntu5.20.04.2","4.4.1-2.1ubuntu5.20.04.3","4.4.1-2.1ubuntu5.20.04.4","4.4.1-2.1ubuntu5.20.04.5"],"ecosystem_specific":{"binaries":[{"binary_version":"4.4.1-2.1ubuntu5.20.04.5","binary_name":"isc-dhcp-client"},{"binary_name":"isc-dhcp-client-ddns","binary_version":"4.4.1-2.1ubuntu5.20.04.5"},{"binary_version":"4.4.1-2.1ubuntu5.20.04.5","binary_name":"isc-dhcp-common"},{"binary_name":"isc-dhcp-relay","binary_version":"4.4.1-2.1ubuntu5.20.04.5"},{"binary_name":"isc-dhcp-server","binary_version":"4.4.1-2.1ubuntu5.20.04.5"},{"binary_name":"isc-dhcp-server-ldap","binary_version":"4.4.1-2.1ubuntu5.20.04.5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"}},{"package":{"name":"isc-dhcp","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/isc-dhcp?arch=source&distr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