Subject: [ASA-202004-16] openvpn: denial of service

Arch Linux Security Advisory ASA-202004-16
==========================================

Severity: Medium
Date    : 2020-04-17
CVE-ID  : CVE-2020-11810
Package : openvpn
Type    : denial of service
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1135

Summary
=======

The package openvpn before version 2.4.9-1 is vulnerable to denial of
service.

Resolution
==========

Upgrade to 2.4.9-1.

# pacman -Syu "openvpn>=2.4.9-1"

The problem has been fixed upstream in version 2.4.9.

Workaround
==========

None.

Description
===========

A security issue has been found in OpenVPN before 2.4.9, where a 'peer-
id' check is not performed correctly during a small amount of time
after a connection has been established. A rogue client sending a data
channel packet during that time, from a different source address and
with the same 'peer-id', would cause the client data to float to that
new address, effectively sopping the VPN traffic of the first,
legitimate client.

Impact
======

A remote attacker might be able to cause the legitimate VPN session of
another client to stall, by sending a crafted packet right at the
beginning of the VPN session.

References
==========

https://github.com/OpenVPN/openvpn/commit/37bc691e7d26ea4eb61a8a434ebd7a9ae76225ab
https://community.openvpn.net/openvpn/ticket/1272
https://security.archlinux.org/CVE-2020-11810