OpenSSH < 10.3 Multiple Vulnerabilities

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(306743);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/04/17");

  script_cve_id(
    "CVE-2026-35385",
    "CVE-2026-35386",
    "CVE-2026-35387",
    "CVE-2026-35388",
    "CVE-2026-35414"
  );
  script_xref(name:"IAVA", value:"2026-A-0296");

  script_name(english:"OpenSSH < 10.3 Multiple Vulnerabilities");

  script_set_attribute(attribute:"synopsis", value:
"The SSH server running on the remote host is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The version of OpenSSH installed on the remote host is prior to 10.3. It is, therefore, affected by multiple
vulnerabilities as referenced in the release-10.3 advisory.

  - In OpenSSH before 10.3, validation of shell metacharacters in user names supplied on the command-line
    was performed too late, allowing potential expansion from %-tokens in ssh_config. For configurations
    that use a %u token in a Match exec block, an attacker who can control the user name passed to ssh(1)
    could potentially execute arbitrary shell commands. (CVE-2026-35386)

  - In OpenSSH before 10.3, a file downloaded by scp may be installed setuid or setgid, an outcome contrary 
    to some users' expectations, if the download is performed as root with -O (legacy scp protocol) and 
    without -p (preserve mode). (CVE-2026-35385)

  - OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in 
    PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.
    (CVE-2026-35387)

  - In OpenSSH before 10.3, connection multiplexing confirmation (requested using ControlMaster ask/autoask)
    was not being tested for proxy mode multiplexing sessions (i.e. ssh -O proxy ...). (CVE-2026-35388)

  - OpenSSH before 10.3 mishandles the authorized_keys principals option in uncommon scenarios involving a 
    principals list in conjunction with a Certificate Authority that makes certain use of comma characters. 
    (CVE-2026-35414)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://www.openssh.com/txt/release-10.3");
  script_set_attribute(attribute:"solution", value:
"Upgrade to OpenSSH version 10.3 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-35414");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/04/02");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/04/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/04/16");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:openbsd:openssh");
  script_set_attribute(attribute:"generated_plugin", value:"former");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("openssh_detect.nbin");
  script_require_keys("installed_sw/OpenSSH");
  script_require_ports("Services/ssh", 22);

  exit(0);
}


include('backport.inc');
include('vcf.inc');
include('vcf_extras.inc');

var port = get_service(svc:'ssh', default:22, exit_on_fail:TRUE);
var app_info = vcf::openssh::get_app_info(app:'OpenSSH', port:port);

vcf::check_all_backporting(app_info:app_info);

var constraints = [
  {'fixed_version': '10.3'}
];

vcf::openssh::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_HOLE);