TencentOS Server 3: openssh (TSSA-2026:0392)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:0392.
##

include('compat.inc');

if (description)
{
  script_id(324637);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/02");

  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:"TencentOS Server 3: openssh (TSSA-2026:0392)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 3 host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0392 advisory.

    Package updates are available for TencentOS Server 3 that fix the following vulnerabilities:

    CVE-2026-35385:
    A flaw was found in OpenSSH. When the `scp` command is used by a root user to download a file with the
    legacy protocol option (`-O`) and without preserving original file permissions (`-p`), the downloaded file
    can be installed with elevated privileges (setuid or setgid). This unexpected behavior could allow a
    malicious file to execute with higher permissions than intended, posing a security risk through potential
    privilege escalation.

    CVE-2026-35386:
    A flaw was found in OpenSSH. This vulnerability allows a remote attacker to achieve arbitrary command
    execution by injecting shell metacharacters into a username provided on the command line. Exploitation
    requires an untrusted username and a non-default configuration of the '%' character in `ssh_config`.

    CVE-2026-35387:
    A flaw was found in OpenSSH. This vulnerability allows the system to use unintended Elliptic Curve Digital
    Signature Algorithm (ECDSA) algorithms. This occurs because the configuration for accepted public key
    algorithms is misinterpreted, leading to the use of weaker cryptographic methods than intended. This could
    potentially allow an attacker to compromise the confidentiality of data.

    CVE-2026-35388:
    A flaw was found in OpenSSH. This vulnerability allows for a low integrity impact due to the omission of
    connection multiplexing confirmation for proxy-mode multiplexing sessions. A local user, under specific
    and complex conditions requiring user interaction, could potentially establish a multiplexed session
    without explicit confirmation, leading to unintended data handling.

    CVE-2026-35414:
    A flaw was found in OpenSSH. This vulnerability arises from the incorrect handling of the authorized_keys
    principals option in uncommon scenarios. Specifically, when a principals list is used with a Certificate
    Authority that includes comma characters, OpenSSH may misinterpret the input. This could lead to security
    bypasses, potentially allowing unintended access or information disclosure in specific authentication
    contexts.

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

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://mirrors.tencent.com/tlinux/errata/tssa-20260392.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  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:"2026/05/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/02");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:openssh");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tencent Local Security Checks");

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

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/etc/os-release", "Host/TencentOS/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'TencentOS' >!< os_product) audit(AUDIT_OS_NOT, 'TencentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'TencentOS');
if (! preg(pattern:"^3([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 3.x', 'TencentOS ' + os_version);

if (!get_kb_item('Host/TencentOS/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'TencentOS', cpu);

var constraints = [
  {
    'release': '3',
    'pkgs': [
      {'reference':'openssh-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-debugsource-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-debugsource-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-debuginfo-8.0p1-29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.3-7.29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.3-7.29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'pam_ssh_agent_auth-debuginfo-0.10.3-7.29.tl3.ap.1', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'pam_ssh_agent_auth-debuginfo-0.10.3-7.29.tl3.ap.1', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'openssh / openssh-askpass / openssh-askpass-debuginfo / etc');
}