Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenSSH vulnerabilities (USN-8533-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8533-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(326800);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/14");

  script_cve_id(
    "CVE-2026-59995",
    "CVE-2026-59996",
    "CVE-2026-59997",
    "CVE-2026-59998",
    "CVE-2026-59999",
    "CVE-2026-60000",
    "CVE-2026-60001",
    "CVE-2026-60002"
  );
  script_xref(name:"USN", value:"8533-1");

  script_name(english:"Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenSSH vulnerabilities (USN-8533-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8533-1 advisory.

    It was discovered that OpenSSH sftp did not properly constrain the location of downloaded files when
    connecting to an attacker-controlled server. An attacker could possibly use this issue to write files to
    unintended locations on the file system. (CVE-2026-59995)

    It was discovered that OpenSSH scp could place files in the parent directory of the intended destination
    when copying between two remote hosts. An attacker could possibly use this issue to write files to
    unintended locations. (CVE-2026-59996)

    It was discovered that OpenSSH internal-sftp only recognized the first nine command-line arguments, This
    could result in certain security-sensitive arguments being ignored, contrary to expectations.
    (CVE-2026-59997)

    It was discovered that OpenSSH had undocumented behaviour regarding the GSSAPIStrictAcceptorCheck option
    in environments using Windows Active Directory. The documentation has been updated to clarify use of the
    option. (CVE-2026-59998)

    It was discovered that OpenSSH did not properly enforce precedence of DisableForwarding=yes over
    PermitTunnel=yes in server configurations. This could possibly result in intended network forwarding
    restrictions being bypassed, contrary to expectations. (CVE-2026-59999)

    It was discovered that OpenSSH mishandled the MaxAuthTries limit for GSSAPI authentication. A remote
    attacker could use this issue to perform excessive authentication attempts. (CVE-2026-60000)

    It was discovered that OpenSSH did not always honour the minimum authentication delay. An attacker could
    possibly use this issue to perform brute-force attacks more efficiently. (CVE-2026-60001)

    It was discovered that the OpenSSH client had a use-after-free vulnerability when a server changed its
    host key during a key re-exchange. An attacker able to intercept communications could possibly use this
    issue to execute arbitrary code or obtain sensitive information. (CVE-2026-60002)

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.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-8533-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-60002");

  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:"2026/07/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/14");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:openssh-client");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:openssh-client-gssapi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:openssh-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:openssh-server-gssapi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:openssh-sftp-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:openssh-tests");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ssh-askpass-gnome");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('22.04' >< os_release || '24.04' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 22.04 / 24.04 / 26.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) 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, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '22.04', 'pkgname': 'openssh-client', 'pkgver': '1:8.9p1-3ubuntu0.16'},
    {'osver': '22.04', 'pkgname': 'openssh-server', 'pkgver': '1:8.9p1-3ubuntu0.16'},
    {'osver': '22.04', 'pkgname': 'openssh-sftp-server', 'pkgver': '1:8.9p1-3ubuntu0.16'},
    {'osver': '22.04', 'pkgname': 'openssh-tests', 'pkgver': '1:8.9p1-3ubuntu0.16'},
    {'osver': '22.04', 'pkgname': 'ssh', 'pkgver': '1:8.9p1-3ubuntu0.16'},
    {'osver': '22.04', 'pkgname': 'ssh-askpass-gnome', 'pkgver': '1:8.9p1-3ubuntu0.16'},
    {'osver': '24.04', 'pkgname': 'openssh-client', 'pkgver': '1:9.6p1-3ubuntu13.18'},
    {'osver': '24.04', 'pkgname': 'openssh-server', 'pkgver': '1:9.6p1-3ubuntu13.18'},
    {'osver': '24.04', 'pkgname': 'openssh-sftp-server', 'pkgver': '1:9.6p1-3ubuntu13.18'},
    {'osver': '24.04', 'pkgname': 'openssh-tests', 'pkgver': '1:9.6p1-3ubuntu13.18'},
    {'osver': '24.04', 'pkgname': 'ssh', 'pkgver': '1:9.6p1-3ubuntu13.18'},
    {'osver': '24.04', 'pkgname': 'ssh-askpass-gnome', 'pkgver': '1:9.6p1-3ubuntu13.18'},
    {'osver': '26.04', 'pkgname': 'openssh-client', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'openssh-client-gssapi', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'openssh-server', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'openssh-server-gssapi', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'openssh-sftp-server', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'openssh-tests', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'ssh', 'pkgver': '1:10.2p1-2ubuntu3.4'},
    {'osver': '26.04', 'pkgname': 'ssh-askpass-gnome', 'pkgver': '1:10.2p1-2ubuntu3.4'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'openssh-client / openssh-client-gssapi / openssh-server / etc');
}