A Kerberos security update has been released for Ubuntu Linux 20.04 LTS, 22.04 LTS, and 23.04.

[USN-6467-2] Kerberos vulnerability

==========================================================================
Ubuntu Security Notice USN-6467-2
November 06, 2023

krb5 vulnerability
==========================================================================

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

- Ubuntu 23.04
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

Kerberos could be made to crash if it received specially crafted
network traffic.

Software Description:
- krb5: MIT Kerberos Network Authentication Protocol

Details:

USN-6467-1 fixed a vulnerability in Kerberos. This update provides the
corresponding update for Ubuntu 20.04 LTS, Ubuntu 22.04 LTS and Ubuntu
23.04.

Original advisory details:

Robert Morris discovered that Kerberos did not properly handle memory
access when processing RPC data through kadmind, which could lead to the
freeing of uninitialized memory. An authenticated remote attacker could
possibly use this issue to cause kadmind to crash, resulting in a denial
of service.

Update instructions:

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

Ubuntu 23.04:
krb5-admin-server 1.20.1-1ubuntu0.1
krb5-kdc 1.20.1-1ubuntu0.1
krb5-kdc-ldap 1.20.1-1ubuntu0.1
krb5-otp 1.20.1-1ubuntu0.1
krb5-pkinit 1.20.1-1ubuntu0.1
krb5-user 1.20.1-1ubuntu0.1
libgssapi-krb5-2 1.20.1-1ubuntu0.1
libgssrpc4 1.20.1-1ubuntu0.1
libk5crypto3 1.20.1-1ubuntu0.1
libkadm5clnt-mit12 1.20.1-1ubuntu0.1
libkadm5srv-mit12 1.20.1-1ubuntu0.1
libkdb5-10 1.20.1-1ubuntu0.1
libkrad0 1.20.1-1ubuntu0.1
libkrb5-3 1.20.1-1ubuntu0.1
libkrb5support0 1.20.1-1ubuntu0.1

Ubuntu 22.04 LTS:
krb5-admin-server 1.19.2-2ubuntu0.3
krb5-kdc 1.19.2-2ubuntu0.3
krb5-kdc-ldap 1.19.2-2ubuntu0.3
krb5-otp 1.19.2-2ubuntu0.3
krb5-pkinit 1.19.2-2ubuntu0.3
krb5-user 1.19.2-2ubuntu0.3
libgssapi-krb5-2 1.19.2-2ubuntu0.3
libgssrpc4 1.19.2-2ubuntu0.3
libk5crypto3 1.19.2-2ubuntu0.3
libkadm5clnt-mit12 1.19.2-2ubuntu0.3
libkadm5srv-mit12 1.19.2-2ubuntu0.3
libkdb5-10 1.19.2-2ubuntu0.3
libkrad0 1.19.2-2ubuntu0.3
libkrb5-3 1.19.2-2ubuntu0.3
libkrb5support0 1.19.2-2ubuntu0.3

Ubuntu 20.04 LTS:
krb5-admin-server 1.17-6ubuntu4.4
krb5-kdc 1.17-6ubuntu4.4
krb5-kdc-ldap 1.17-6ubuntu4.4
krb5-otp 1.17-6ubuntu4.4
krb5-pkinit 1.17-6ubuntu4.4
krb5-user 1.17-6ubuntu4.4
libgssapi-krb5-2 1.17-6ubuntu4.4
libgssrpc4 1.17-6ubuntu4.4
libk5crypto3 1.17-6ubuntu4.4
libkadm5clnt-mit11 1.17-6ubuntu4.4
libkadm5srv-mit11 1.17-6ubuntu4.4
libkdb5-9 1.17-6ubuntu4.4
libkrad0 1.17-6ubuntu4.4
libkrb5-3 1.17-6ubuntu4.4
libkrb5support0 1.17-6ubuntu4.4

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

References:
https://ubuntu.com/security/notices/USN-6467-2
https://ubuntu.com/security/notices/USN-6467-1
CVE-2023-36054

Package Information:
https://launchpad.net/ubuntu/+source/krb5/1.20.1-1ubuntu0.1
https://launchpad.net/ubuntu/+source/krb5/1.19.2-2ubuntu0.3
https://launchpad.net/ubuntu/+source/krb5/1.17-6ubuntu4.4