[USN-8222-1] OpenSSH vulnerabilities

========================================================================== Ubuntu Security Notice USN-8222-1 April 29, 2026 openssh vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 26.04 LTS - 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: Christos Papakonstantinou discovered that the OpenSSH scp tool incorrectly handled the legacy scp protocol (-O) option. This could result in certain files being installed setuid or setgid, contrary to expectations. (CVE-2026-35385) Florian Kohnhäuser discovered that OpenSSH incorrectly handled shell metacharacters in usernames within a command line. When untrusted usernames and non-default configurations using % in ssh_config are being used, an attacker could possibly use this issue to execute arbitrary code. (CVE-2026-35386) Christos Papakonstantinou discovered that OpenSSH incorrectly handled parsing the PubkeyAcceptedAlgorithms and HostbasedAcceptedAlgorithms options. This could result in unintended ECDSA algorithms being used, contrary to expectations. (CVE-2026-35387) Michalis Vasileiadis discovered that OpenSSH incorrectly handled proxy-mode multiplexing sessions. This could result in no confirmation being asked, contrary to expectations. (CVE-2026-35388) Vladimir Tokarev discovered that OpenSSH incorrectly handled certificates with the principal name containing a comma character when using user-trusted CA keys in authorized_keys and an authorized_keys principals="" option that lists more than one principal. This could result in inappropriate principal matching, contrary to expectations. (CVE-2026-35414) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS openssh-client 1:10.2p1-2ubuntu3.2 openssh-server 1:10.2p1-2ubuntu3.2 Ubuntu 25.10 openssh-client 1:10.0p1-5ubuntu5.4 openssh-server 1:10.0p1-5ubuntu5.4 Ubuntu 24.04 LTS openssh-client 1:9.6p1-3ubuntu13.16 openssh-server 1:9.6p1-3ubuntu13.16 Ubuntu 22.04 LTS openssh-client 1:8.9p1-3ubuntu0.15 openssh-server 1:8.9p1-3ubuntu0.15 In general, a standard system update will make all the necessary changes. References: https://ubuntu.com/security/notices/USN-8222-1 CVE-2026-35385, CVE-2026-35386, CVE-2026-35387, CVE-2026-35388, CVE-2026-35414 Package Information: https://launchpad.net/ubuntu/+source/openssh/1:10.2p1-2ubuntu3.2 https://launchpad.net/ubuntu/+source/openssh/1:10.0p1-5ubuntu5.4 https://launchpad.net/ubuntu/+source/openssh/1:9.6p1-3ubuntu13.16 https://launchpad.net/ubuntu/+source/openssh/1:8.9p1-3ubuntu0.15