Ubuntu 20.04 LTS / 22.04 LTS : Linux kernel vulnerabilities (USN-8388-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8388-1. 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(318842);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/11");

  script_cve_id(
    "CVE-2026-43284",
    "CVE-2026-43494",
    "CVE-2026-43500",
    "CVE-2026-43503",
    "CVE-2026-46300",
    "CVE-2026-46333"
  );
  script_xref(name:"USN", value:"8388-1");

  script_name(english:"Ubuntu 20.04 LTS / 22.04 LTS : Linux kernel vulnerabilities (USN-8388-1)");

  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 20.04 LTS / 22.04 LTS host has a package installed that is affected by multiple vulnerabilities as
referenced in the USN-8388-1 advisory.

    It was discovered that the Linux kernel did not properly handle shared page fragments during socket buffer
    operations, collectively known as Dirty Frag. A logic flaw existed in the XFRM ESP-in-TCP subsystem and in
    the RxRPC networking subsystem when processing paged fragments. A local attacker could use this to
    escalate privileges, or possibly escape a container. (CVE-2026-43284, CVE-2026-43500)

    It was discovered that a logic flaw existed in the XFRM ESP-in-TCP subsystem in the Linux kernel when
    handling socket buffer fragments. This flaw is known as Fragnesia. A local attacker could use this to
    escalate privileges, or possibly escape a container. (CVE-2026-43503, CVE-2026-46300)

    Qualys discovered that a race condition existed in the ptrace subsystem of the Linux kernel when
    privileged processes are exiting. An unprivileged local attacker could use this issue to expose sensitive
    information. (CVE-2026-46333)

    Several security issues were discovered in the Linux kernel. An attacker could possibly use these to
    compromise the system. This update corrects flaws in the following subsystems:

    - RDS protocol; (CVE-2026-43494)

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-8388-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:H/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:H/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-46300");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"exploit_framework_core", value:"true");
  script_set_attribute(attribute:"exploited_by_malware", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'xfrm-ESP Page-Cache Write via CVE-2026-43284');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/05");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1050-nvidia-tegra-igx");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1050-nvidia-tegra-igx-rt");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1061-nvidia-tegra");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1061-nvidia-tegra-rt");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1092-gkeop");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1101-intel-iot-realtime");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1101-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1103-ibm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1103-raspi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1104-intel-iotg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1104-nvidia");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1104-nvidia-lowlatency");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1105-gke");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1106-oracle");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1108-realtime");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1109-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1109-aws-64k");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1109-aws-fips");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1109-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-1109-gcp-fips");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-181-fips");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-181-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-181-generic-64k");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.15.0-181-generic-lpae");
  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", "ubuntu_pro_sub_detect.nasl", "linux_alt_patch_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');
include('ksplice.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 (! ('20.04' >< os_release || '22.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 20.04 / 22.04', '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 ubuntu_pro_detected = get_kb_item('Host/Ubuntu/Pro/Services/esm-apps');
ubuntu_pro_detected = !empty_or_null(ubuntu_pro_detected);

var kernel_mappings = {
  '20.04': {
    '5.15.0': {
      'generic': '5.15.0-181',
      'generic-64k': '5.15.0-181',
      'generic-lpae': '5.15.0-181',
      'nvidia-tegra': '5.15.0-1061',
      'nvidia-tegra-rt': '5.15.0-1061',
      'ibm': '5.15.0-1103',
      'gcp': '5.15.0-1109',
      'aws': '5.15.0-1109'
    }
  },
  '22.04': {
    '5.15.0': {
      'generic': '5.15.0-181',
      'generic-64k': '5.15.0-181',
      'generic-lpae': '5.15.0-181',
      'fips': '5.15.0-181',
      'nvidia-tegra-igx': '5.15.0-1050',
      'nvidia-tegra-igx-rt': '5.15.0-1050',
      'nvidia-tegra': '5.15.0-1061',
      'nvidia-tegra-rt': '5.15.0-1061',
      'gkeop': '5.15.0-1092',
      'kvm': '5.15.0-1101',
      'intel-iot-realtime': '5.15.0-1101',
      'ibm': '5.15.0-1103',
      'raspi': '5.15.0-1103',
      'intel-iotg': '5.15.0-1104',
      'nvidia': '5.15.0-1104',
      'nvidia-lowlatency': '5.15.0-1104',
      'gke': '5.15.0-1105',
      'oracle': '5.15.0-1106',
      'realtime': '5.15.0-1108',
      'aws': '5.15.0-1109',
      'aws-64k': '5.15.0-1109',
      'gcp': '5.15.0-1109',
      'aws-fips': '5.15.0-1109',
      'gcp-fips': '5.15.0-1109'
    }
  }
};

var host_kernel_release = get_kb_item('Host/uptrack-uname-r');
if (empty_or_null(host_kernel_release)) host_kernel_release = get_kb_item_or_exit('Host/uname-r');
var host_kernel_base_version = get_kb_item_or_exit('Host/Debian/kernel-base-version');
var host_kernel_type = get_kb_item_or_exit('Host/Debian/kernel-type');
if(empty_or_null(kernel_mappings[os_release][host_kernel_base_version][host_kernel_type])) audit(AUDIT_INST_VER_NOT_VULN, 'kernel ' + host_kernel_release);

var extra = '';
var kernel_fixed_version = kernel_mappings[os_release][host_kernel_base_version][host_kernel_type] + "-" + host_kernel_type;
if (!ubuntu_pro_detected) {
  extra += 'NOTE: This vulnerability check contains fixes that apply to packages only \n';
  extra += 'available in Ubuntu ESM repositories. Access to these package security updates \n';
  extra += 'require an Ubuntu Pro subscription.\n\n';
}
if (deb_ver_cmp(ver1:host_kernel_release, ver2:kernel_fixed_version) < 0)
{
  extra += 'Running Kernel level of ' + host_kernel_release + ' does not meet the minimum fixed level of ' + kernel_fixed_version + ' for this advisory.\n\n';
}
  else
{
  audit(AUDIT_PATCH_INSTALLED, 'Kernel package for USN-8388-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2026-43284', 'CVE-2026-43494', 'CVE-2026-43500', 'CVE-2026-43503', 'CVE-2026-46300', 'CVE-2026-46333');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-8388-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : extra
  );
  exit(0);
}