==========================================================================
Ubuntu Security Notice USN-8090-1
March 12, 2026

openssh vulnerabilities
==========================================================================

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

- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

Several security issues were fixed in OpenSSH.

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

Details:

Jeremy Brown discovered that the OpenSSH GSSAPI Key Exchange incorrectly
handled disconnecting clients. In non-default configurations where the
GSSAPIKeyExchange setting is enabled, a remote attacker could use this
issue to cause OpenSSH to crash, resulting in a denial of service, or
possibly execute arbitrary code. (CVE-2026-3497)

David Leadbeater discovered that OpenSSH incorrectly handled certain
control characters in usernames. When untrusted usernames and the
ProxyCommand are being used, an attacker could possibly use this issue to
execute arbitrary code. (CVE-2025-61984)

David Leadbeater discovered that OpenSSH incorrectly handled NULL
characters in ssh:// URIs. When the ProxyCommand is being used, an attacker
could possibly use this issue to execute arbitrary code. (CVE-2025-61985)

Update instructions:

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

Ubuntu 25.10
  openssh-client                  1:10.0p1-5ubuntu5.1
  openssh-server                  1:10.0p1-5ubuntu5.1

Ubuntu 24.04 LTS
  openssh-client                  1:9.6p1-3ubuntu13.15
  openssh-server                  1:9.6p1-3ubuntu13.15

Ubuntu 22.04 LTS
  openssh-client                  1:8.9p1-3ubuntu0.14
  openssh-server                  1:8.9p1-3ubuntu0.14

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

References:
  https://ubuntu.com/security/notices/USN-8090-1
  CVE-2025-61984, CVE-2025-61985, CVE-2026-3497

Package Information:
  https://launchpad.net/ubuntu/+source/openssh/1:10.0p1-5ubuntu5.1
  https://launchpad.net/ubuntu/+source/openssh/1:9.6p1-3ubuntu13.15
  https://launchpad.net/ubuntu/+source/openssh/1:8.9p1-3ubuntu0.14