A Kerberos security update has been released for Ubuntu Linux 14.04 ESM, 16.04 ESM, 18.04 LTS, 20.04 LTS, 22.04 LTS, and 22.10.

USN-5828-1: Kerberos vulnerabilities

==========================================================================
Ubuntu Security Notice USN-5828-1
January 25, 2023

krb5 vulnerabilities
==========================================================================

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

- Ubuntu 22.10
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

Several security issues were fixed in Kerberos.

Software Description:
- krb5: MIT Kerberos Network Authentication Protocol

Details:

It was discovered that Kerberos incorrectly handled certain S4U2Self
requests. An attacker could possibly use this issue to cause a denial of
service. This issue was only addressed in Ubuntu 16.04 ESM and Ubuntu
18.04 LTS. (CVE-2018-20217)

Greg Hudson discovered that Kerberos PAC implementation incorrectly
handled certain parsing operations. A remote attacker could use this
issue to cause a denial of service, or possibly execute arbitrary code.
(CVE-2022-42898)

Update instructions:

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

Ubuntu 22.10:
krb5-admin-server 1.20-1ubuntu0.1
krb5-kdc 1.20-1ubuntu0.1
krb5-user 1.20-1ubuntu0.1
libgssapi-krb5-2 1.20-1ubuntu0.1
libkdb5-10 1.20-1ubuntu0.1

Ubuntu 22.04 LTS:
krb5-admin-server 1.19.2-2ubuntu0.1
krb5-kdc 1.19.2-2ubuntu0.1
krb5-user 1.19.2-2ubuntu0.1
libgssapi-krb5-2 1.19.2-2ubuntu0.1
libkdb5-10 1.19.2-2ubuntu0.1

Ubuntu 20.04 LTS:
krb5-admin-server 1.17-6ubuntu4.2
krb5-kdc 1.17-6ubuntu4.2
krb5-user 1.17-6ubuntu4.2
libgssapi-krb5-2 1.17-6ubuntu4.2
libkdb5-9 1.17-6ubuntu4.2

Ubuntu 18.04 LTS:
krb5-admin-server 1.16-2ubuntu0.3
krb5-kdc 1.16-2ubuntu0.3
krb5-user 1.16-2ubuntu0.3
libgssapi-krb5-2 1.16-2ubuntu0.3
libkdb5-9 1.16-2ubuntu0.3

Ubuntu 16.04 ESM:
krb5-admin-server 1.13.2+dfsg-5ubuntu2.2+esm3
krb5-kdc 1.13.2+dfsg-5ubuntu2.2+esm3
krb5-user 1.13.2+dfsg-5ubuntu2.2+esm3
libgssapi-krb5-2 1.13.2+dfsg-5ubuntu2.2+esm3
libkdb5-8 1.13.2+dfsg-5ubuntu2.2+esm3

Ubuntu 14.04 ESM:
krb5-admin-server 1.12+dfsg-2ubuntu5.4+esm3
krb5-kdc 1.12+dfsg-2ubuntu5.4+esm3
krb5-user 1.12+dfsg-2ubuntu5.4+esm3
libgssapi-krb5-2 1.12+dfsg-2ubuntu5.4+esm3
libkdb5-7 1.12+dfsg-2ubuntu5.4+esm3

After a standard system update you need to restart any application
using Kerberos libraries to make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-5828-1
CVE-2018-20217, CVE-2022-42898

Package Information:
https://launchpad.net/ubuntu/+source/krb5/1.20-1ubuntu0.1
https://launchpad.net/ubuntu/+source/krb5/1.19.2-2ubuntu0.1
https://launchpad.net/ubuntu/+source/krb5/1.17-6ubuntu4.2
https://launchpad.net/ubuntu/+source/krb5/1.16-2ubuntu0.3