UBUNTU-CVE-2026-18103

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Source
https://ubuntu.com/security/CVE-2026-18103
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-18103
Upstream
  • CVE-2026-18103
Published
2026-08-05T00:16:00Z
Modified
2026-08-19T11:01:27Z
Severity
  • 4.9 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
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.

References

Affected packages

Ubuntu:18.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
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_name": "isc-dhcp-server-ldap",
            "binary_version": "4.3.5-3ubuntu7.4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"
Ubuntu:20.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
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_name": "isc-dhcp-client",
            "binary_version": "4.4.1-2.1ubuntu5.20.04.5"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.1-2.1ubuntu5.20.04.5"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.1-2.1ubuntu5.20.04.5"
        },
        {
            "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"
Ubuntu:22.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.4.1-2.3ubuntu1
4.4.1-2.3ubuntu2
4.4.1-2.3ubuntu2.1
4.4.1-2.3ubuntu2.2
4.4.1-2.3ubuntu2.3
4.4.1-2.3ubuntu2.4

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.4.1-2.3ubuntu2.4"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.1-2.3ubuntu2.4"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.1-2.3ubuntu2.4"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.4.1-2.3ubuntu2.4"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.4.1-2.3ubuntu2.4"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.4.1-2.3ubuntu2.4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"
Ubuntu:24.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.4.3-P1-2ubuntu5
4.4.3-P1-4ubuntu1
4.4.3-P1-4ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-keama",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.4.3-P1-4ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"
Ubuntu:26.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.4.3-P1-4ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-keama",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.4.3-P1-4ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"
Ubuntu:Pro:14.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=esm-infra-legacy%2Ftrusty

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
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_name": "isc-dhcp-common",
            "binary_version": "4.2.4-7ubuntu12.13+esm2"
        },
        {
            "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_name": "isc-dhcp-server-ldap",
            "binary_version": "4.2.4-7ubuntu12.13+esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18103.json"
Ubuntu:Pro:16.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=esm-infra%2Fxenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
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_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_version": "4.3.3-5ubuntu12.10+esm2"
        },
        {
            "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"