CVE-2020-13529

An exploitable denial of service vulnerability exists in systemd which does not fully implement RFC3203, as it does not support authentication of FORCERENEW packets. A specially crafted DHCP FORCERENEW packet can cause a system, running the DHCP client, to be vulnerable to a DHCP ACK spoofing attack. An attacker can forge a pair of FORCERENEW and DCHPACK packets to reconfigure the system with arbitrary network settings.

This issue did not affect the versions of systemd as shipped with Red Hat Enterprise Linux 8 as they did not include systemd-networkd service.

NetworkManager embeds some pieces of systemd code base, including the DHCP client code. For this reason NetworkManager is marked as affected. By default only the versions of NetworkManager as shipped in Red Hat Enterprise Linux 8.0 and 8.1 are affected, as in those versions NetworkManager uses main.dhcp=internal setting (see networkmanager.conf(5)) by default, which relies on systemd DHCP client. On newer Red Hat Enterprise Linux 8 versions NetworkManager uses a different DHCP client by default, which is not affected by this flaw. On Red Hat Enterprise Linux 7 NetworkManager uses main.dhcp=dhclient by default, which is not affected by this flaw either, however users who have explicitly configured main.dhcp=internal would be affected, as the systemd DHCP client would be used in that case.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

There is no available mitigation for this issue.