An OpenVPN security update has been released for Ubuntu Linux 21.04, 20.10, 20.04 LTS, and 18.04 LTS.

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Ubuntu Security Notice USN-4933-1
May 04, 2021

openvpn vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

everal security issues were fixed in OpenVPN.

Software Description:
- openvpn: virtual private network software

Details:

It was discovered that OpenVPN incorrectly handled certain data channel v2
packets. A remote attacker could possibly use this issue to inject packets
using a victim's peer-id. This issue only affected Ubuntu 18.04 LTS and
Ubuntu 20.04 LTS. (CVE-2020-11810)

It was discovered that OpenVPN incorrectly handled deferred authentication.
When a server is configured to use deferred authentication, a remote
attacker could possibly use this issue to bypass authentication and access
control channel data. (CVE-2020-15078)

Update instructions:

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

Ubuntu 21.04:
openvpn 2.5.1-1ubuntu1.1

Ubuntu 20.10:
openvpn 2.4.9-3ubuntu1.1

Ubuntu 20.04 LTS:
openvpn 2.4.7-1ubuntu2.20.04.2

Ubuntu 18.04 LTS:
openvpn 2.4.4-2ubuntu1.5

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

References:
  https://ubuntu.com/security/notices/USN-4933-1
CVE-2020-11810, CVE-2020-15078

Package Information:
  https://launchpad.net/ubuntu/+source/openvpn/2.5.1-1ubuntu1.1
  https://launchpad.net/ubuntu/+source/openvpn/2.4.9-3ubuntu1.1
  https://launchpad.net/ubuntu/+source/openvpn/2.4.7-1ubuntu2.20.04.2
  https://launchpad.net/ubuntu/+source/openvpn/2.4.4-2ubuntu1.5