A GnuTLS security update has been released for Ubuntu Linux 20.04 LTS.

USN-4491-1: GnuTLS vulnerability

==========================================================================
Ubuntu Security Notice USN-4491-1
September 09, 2020

gnutls28 vulnerability
==========================================================================

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

- Ubuntu 20.04 LTS

Summary:

GnuTLS could be made to crash or run programs if it received specially
crafted network traffic.

Software Description:
- gnutls28: GNU TLS library

Details:

It was discovered that GnuTLS incorrectly handled certain alerts when being
used with TLS 1.3 servers. A remote attacker could use this issue to cause
GnuTLS to crash, resulting in a denial of service, or possibly execute
arbitrary code.

Update instructions:

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

Ubuntu 20.04 LTS:
libgnutls30 3.6.13-2ubuntu1.3

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

References:
  https://usn.ubuntu.com/4491-1
CVE-2020-24659

Package Information:
  https://launchpad.net/ubuntu/+source/gnutls28/3.6.13-2ubuntu1.3