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Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : OpenSSH vulnerabilities (USN-8222-1)

high Nessus Plugin ID 311107

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Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8222-1 advisory.

 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 Kohnhuser 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)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-8222-1

Plugin Details

Severity: High

ID: 311107

File Name: ubuntu_USN-8222-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 4/30/2026

Updated: 4/30/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 7.6

Temporal Score: 5.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-35414

CVSS v3

Risk Factor: High

Base Score: 8.1

Temporal Score: 7.1

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:canonical:ubuntu_linux:openssh-client-gssapi, cpe:/o:canonical:ubuntu_linux:25.10, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:openssh-server-gssapi, p-cpe:/a:canonical:ubuntu_linux:openssh-client, p-cpe:/a:canonical:ubuntu_linux:ssh, p-cpe:/a:canonical:ubuntu_linux:openssh-tests, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:openssh-server, p-cpe:/a:canonical:ubuntu_linux:ssh-askpass-gnome, p-cpe:/a:canonical:ubuntu_linux:openssh-sftp-server

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 4/29/2026

Vulnerability Publication Date: 4/2/2026

Reference Information

CVE: CVE-2026-35385, CVE-2026-35386, CVE-2026-35387, CVE-2026-35388, CVE-2026-35414

IAVA: 2026-A-0296

USN: 8222-1