A pam_tacplus security update has been released for Ubuntu Linux 20.04 LTS, 18.04 LTS, and 16.04 LTS to address an issue where pam_tacplus did not properly manage shared secrets if DEBUG loglevel and journald are used. 

USN-4521-1: pam_tacplus vulnerability

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Ubuntu Security Notice USN-4521-1
September 21, 2020

libpam-tacplus vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

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

Summary:

pam_tacplus could be made to expose sensitive information.

Software Description:
- libpam-tacplus: PAM module for using TACACS+ as an authentication service

Details:

It was discovered that pam_tacplus did not properly manage shared
secrets if DEBUG loglevel and journald are used. A remote attacker could
use this issue to expose sensitive information.

Update instructions:

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

Ubuntu 20.04 LTS:
libpam-tacplus 1.3.8-2+deb8u1build0.20.04.1

Ubuntu 18.04 LTS:
libpam-tacplus 1.3.8-2+deb8u1build0.18.04.1

Ubuntu 16.04 LTS:
libpam-tacplus 1.3.8-2+deb8u1build0.16.04.1

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

References:
https://usn.ubuntu.com/4521-1
CVE-2020-13881

Package Information:

https://launchpad.net/ubuntu/+source/libpam-tacplus/1.3.8-2+deb8u1build0.20.04.1

https://launchpad.net/ubuntu/+source/libpam-tacplus/1.3.8-2+deb8u1build0.18.04.1

https://launchpad.net/ubuntu/+source/libpam-tacplus/1.3.8-2+deb8u1build0.16.04.1