USN-4969-1: DHCP vulnerability

Releases

• Ubuntu 21.04
• Ubuntu 20.10
• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM

Packages

• isc-dhcp - DHCP server and client

Details

Jon Franklin and Pawel Wieczorkiewicz discovered that DHCP incorrectly
handled lease file parsing. A remote attacker could possibly use this issue
to cause DHCP to crash, resulting in a denial of service.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.04

• isc-dhcp-client - 4.4.1-2.2ubuntu6.1
• isc-dhcp-server - 4.4.1-2.2ubuntu6.1

Ubuntu 20.10

• isc-dhcp-client - 4.4.1-2.1ubuntu10.1
• isc-dhcp-server - 4.4.1-2.1ubuntu10.1

Ubuntu 20.04

• isc-dhcp-client - 4.4.1-2.1ubuntu5.20.04.2
• isc-dhcp-server - 4.4.1-2.1ubuntu5.20.04.2

Ubuntu 18.04

• isc-dhcp-client - 4.3.5-3ubuntu7.3
• isc-dhcp-server - 4.3.5-3ubuntu7.3

In general, a standard system update will make all the necessary changes.

References

• CVE-2021-25217

Related notices

• USN-4969-2: isc-dhcp, isc-dhcp-client, isc-dhcp-client-ddns, isc-dhcp-client-udeb, isc-dhcp-dev, isc-dhcp-client-noddns, isc-dhcp-server, isc-dhcp-server-ldap, isc-dhcp-relay, isc-dhcp-common