Affected: OpenBSD OpenSSH

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.

Affected: Ubuntu:22.04:LTS: openssh, Ubuntu:24.04:LTS: openssh, Ubuntu:26.04:LTS: openssh

It was discovered that OpenSSH's ssh-agent incorrectly handled interactions between agent locking and the session-bind@openssh.com extension. A remote attacker with access to a forwarded agent connection could possibly use this issue to perform operations that should only be available locally, such as adding tokens or using keys. (CVE-2026-73281)

It was discovered that OpenSSH's ssh client incorrectly handled concurrent remote-forwarding operations. A remote attacker could possibly use this issue to cause a use-after-free condition, resulting in a denial of service or the execution of arbitrary code. (CVE-2026-73282)

It was discovered that OpenSSH's sshd server incorrectly applied the restrict keyword from authorized_keys to tunnel forwarding requests. A local attacker with an authorized key could possibly use this issue to bypass intended tunnel forwarding restrictions. (CVE-2026-73283)