# CVE-2018-5733: isc-dhcp-client: A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can...

CVE-2018-5733 is fixed in 6 products on 1 platform, first by isc-dhcp-client 4.3.5-3ubuntu5, released February 28, 2018. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2018-5733
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.2024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 28, 2018

## Description

A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can eventually overflow a 32-bit reference counter, potentially causing dhcpd to crash. Affects ISC DHCP 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | isc-dhcp-client Ubuntu 18.04.6 LTS (bionic) | 4.3.5-3ubuntu5 | [isc-dhcp-client 4.3.5-3ubuntu5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-isc-dhcp-client-4.3.5-3ubuntu5.md) | Feb 28, 2018 |
| Linux | isc-dhcp-client-ddns Ubuntu 18.04.6 LTS (bionic) | 4.3.5-3ubuntu5 | [isc-dhcp-client-ddns 4.3.5-3ubuntu5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-isc-dhcp-client-ddns-4.3.5-3ubuntu5.md) | Feb 28, 2018 |
| Linux | isc-dhcp-common Ubuntu 18.04.6 LTS (bionic) | 4.3.5-3ubuntu5 | [isc-dhcp-common 4.3.5-3ubuntu5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-isc-dhcp-common-4.3.5-3ubuntu5.md) | Feb 28, 2018 |
| Linux | isc-dhcp-relay Ubuntu 18.04.6 LTS (bionic) | 4.3.5-3ubuntu5 | [isc-dhcp-relay 4.3.5-3ubuntu5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-isc-dhcp-relay-4.3.5-3ubuntu5.md) | Feb 28, 2018 |
| Linux | isc-dhcp-server Ubuntu 18.04.6 LTS (bionic) | 4.3.5-3ubuntu5 | [isc-dhcp-server 4.3.5-3ubuntu5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-isc-dhcp-server-4.3.5-3ubuntu5.md) | Feb 28, 2018 |
| Linux | isc-dhcp-server-ldap Ubuntu 18.04.6 LTS (bionic) | 4.3.5-3ubuntu5 | [isc-dhcp-server-ldap 4.3.5-3ubuntu5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-isc-dhcp-server-ldap-4.3.5-3ubuntu5.md) | Feb 28, 2018 |

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Data as of 2026-11-07T12:40:37Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo