A systemd security update has been released for Arch Linux.

ASA-202107-29: systemd: denial of service

Arch Linux Security Advisory ASA-202107-29
=========================================
Severity: Low
Date : 2021-07-14
CVE-ID : CVE-2020-13529
Package : systemd
Type : denial of service
Remote : Yes
Link :   https://security.archlinux.org/AVG-1935

Summary
======
The package systemd before version 249-2 is vulnerable to denial of
service.

Resolution
=========
Upgrade to 249-2.

# pacman -Syu "systemd>$9-2"

The problem has been fixed upstream in version 249.

Workaround
=========
None.

Description
==========
An exploitable denial-of-service vulnerability exists in systemd-
networkd before version 249. A maliciously crafted DHCP FORCERENEW
packet can cause a server running the DHCP client to be vulnerable to a
DHCP ACK spoofing attack. An attacker can forge a pair of FORCERENEW
and DCHP ACK packets to reconfigure the server.

Impact
=====
A network-adjacent attacker could reconfigure the networking properties
of a device running systemd-networkd through crafted DHCP packets.

References
=========
  https://talosintelligence.com/vulnerability_reports/TALOS-2020-1142
  https://github.com/systemd/systemd/issues/16774
  https://github.com/systemd/systemd/pull/20002
  https://github.com/systemd/systemd/commit/38e980a6a5a3442c2f48b1f827284388096d8ca5
  https://security.archlinux.org/CVE-2020-13529