An OpenSSH security update has been released for Ubuntu Linux 20.04 LTS, 22.04 LTS, and 23.04.

[USN-6242-1] OpenSSH vulnerability

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Ubuntu Security Notice USN-6242-1
July 24, 2023

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

- Ubuntu 23.04
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

OpenSSH could be made to run programs as your login when using ssh-agent
forwarding.

Software Description:
- openssh: secure shell (SSH) for secure access to remote machines

Details:

It was discovered that OpenSSH incorrectly handled loading certain PKCS#11
providers. If a user forwarded their ssh-agent to an untrusted system, a
remote attacker could possibly use this issue to load arbitrary libraries
from the user's system and execute arbitrary code.

Update instructions:

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

Ubuntu 23.04:
openssh-client 1:9.0p1-1ubuntu8.4

Ubuntu 22.04 LTS:
openssh-client 1:8.9p1-3ubuntu0.3

Ubuntu 20.04 LTS:
openssh-client 1:8.2p1-4ubuntu0.8

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

References:
https://ubuntu.com/security/notices/USN-6242-1
CVE-2023-38408

Package Information:
https://launchpad.net/ubuntu/+source/openssh/1:9.0p1-1ubuntu8.4
https://launchpad.net/ubuntu/+source/openssh/1:8.9p1-3ubuntu0.3
https://launchpad.net/ubuntu/+source/openssh/1:8.2p1-4ubuntu0.8