An Apache Log4net security update has been released for Ubuntu 16.04 LTS, 18.04 LTS, 20.04 LTS, and 20.10.

USN-4699-1: Apache Log4net vulnerability

=========================================================================
Ubuntu Security Notice USN-4699-1
January 19, 2021

log4net vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Apache Log4net could made to expose sensitive information if it
received a specially crafted configuration file.

Software Description:
- log4net: Highly configurable logging API for the CLI log4net

Details:

It was discovered that Apache Log4net incorrectly handled certain configuration files.
An attacker could possibly use this issue to expose sensitive information.

Update instructions:

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

Ubuntu 20.10:
liblog4net1.2-cil 1.2.10+dfsg-7ubuntu0.20.10.1

Ubuntu 20.04 LTS:
liblog4net1.2-cil 1.2.10+dfsg-7ubuntu0.20.04.1

Ubuntu 18.04 LTS:
liblog4net1.2-cil 1.2.10+dfsg-7ubuntu0.18.04.1

Ubuntu 16.04 LTS:
liblog4net1.2-cil 1.2.10+dfsg-7ubuntu0.16.04.1

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

References:
  https://usn.ubuntu.com/4699-1
CVE-2018-1285

Package Information:
  https://launchpad.net/ubuntu/+source/log4net/1.2.10+dfsg-7ubuntu0.20.10.1
  https://launchpad.net/ubuntu/+source/log4net/1.2.10+dfsg-7ubuntu0.20.04.1
  https://launchpad.net/ubuntu/+source/log4net/1.2.10+dfsg-7ubuntu0.18.04.1
  https://launchpad.net/ubuntu/+source/log4net/1.2.10+dfsg-7ubuntu0.16.04.1