RHEL 8 : kernel-rt (RHSA-2026:50979)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory RHSA-2026:50979. The text
# itself is copyright (C) Red Hat, Inc.
##

include('compat.inc');

if (description)
{
  script_id(332970);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/06");

  script_cve_id("CVE-2025-54518");
  script_xref(name:"RHSA", value:"2026:50979");

  script_name(english:"RHEL 8 : kernel-rt (RHSA-2026:50979)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in
the RHSA-2026:50979 advisory.

    The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with
    extremely high determinism requirements.

    Security Fix(es):

    * kernel: xen: AMD Zen 2 Processors: Privilege escalation via improper CPU cache isolation
    (CVE-2025-54518)

    Bug Fix(es) and Enhancement(s):

    * Kernel crash in bpf_for_each_array_elem() due to missing backport of upstream commit 4b6313cf99b0
    (JIRA:RHEL-191844)

    * gfs2: xfstests generic/363 failure [rhel-8.10.z] (JIRA:RHEL-214099)

    * RHEL8: HYPERV hv_storvsc driver can we add additional code to allow PERSISTENT_RESERVE_IN [RHEL 8.10Z]
    (JIRA:RHEL-188270)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and
    other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/updates/classification/#important");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2477784");
  # https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_50979.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?fe94d1ac");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2026:50979");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/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:L/AC:H/PR:L/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:"cvss4_vector", value:"CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2025-54518");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(1220);
  script_set_attribute(attribute:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/06");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:rhel_eus:8.10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-extra");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-extra");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Red Hat 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_info.nasl", "redhat_repos.nasl", "linux_alt_patch_detect.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');
include('rhel.inc');
include('ksplice.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) || 'Red Hat' >!< os_product) audit(AUDIT_OS_NOT, 'Red Hat');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
if (!rhel_check_release(operator: 'ge', os_version: os_version, rhel_version: '8')) audit(AUDIT_OS_NOT, 'Red Hat 8.x', 'Red Hat ' + os_version);

if (!get_kb_item('Host/RedHat/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 && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Red Hat', cpu);

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var livepatch_source = get_one_kb_item('Host/livepatch-kernel-source');
  if (empty_or_null(livepatch_source)) livepatch_source = 'KSplice';
  rm_kb_item(name:'Host/livepatch-kernel-version');

  var cve_list = make_list('CVE-2025-54518');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, livepatch_source + ' hotfix for RHSA-2026:50979');
  }
  else
  {
    __rpm_report = ksplice_reporting_text();
  }
}

var constraints = [
  {
    'release': '8',
    'repo_relative_urls': [
      'content/dist/rhel8/8.10/x86_64/nfv/debug',
      'content/dist/rhel8/8.10/x86_64/nfv/os',
      'content/dist/rhel8/8.10/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.10/x86_64/rt/debug',
      'content/dist/rhel8/8.10/x86_64/rt/os',
      'content/dist/rhel8/8.10/x86_64/rt/source/SRPMS',
      'content/dist/rhel8/8.6/x86_64/nfv/debug',
      'content/dist/rhel8/8.6/x86_64/nfv/os',
      'content/dist/rhel8/8.6/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.6/x86_64/rt/debug',
      'content/dist/rhel8/8.6/x86_64/rt/os',
      'content/dist/rhel8/8.6/x86_64/rt/source/SRPMS',
      'content/dist/rhel8/8.8/x86_64/nfv/debug',
      'content/dist/rhel8/8.8/x86_64/nfv/os',
      'content/dist/rhel8/8.8/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.8/x86_64/rt/debug',
      'content/dist/rhel8/8.8/x86_64/rt/os',
      'content/dist/rhel8/8.8/x86_64/rt/source/SRPMS',
      'content/dist/rhel8/8.9/x86_64/nfv/debug',
      'content/dist/rhel8/8.9/x86_64/nfv/os',
      'content/dist/rhel8/8.9/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.9/x86_64/rt/debug',
      'content/dist/rhel8/8.9/x86_64/rt/os',
      'content/dist/rhel8/8.9/x86_64/rt/source/SRPMS',
      'content/dist/rhel8/8/x86_64/nfv/debug',
      'content/dist/rhel8/8/x86_64/nfv/os',
      'content/dist/rhel8/8/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8/x86_64/rt/debug',
      'content/dist/rhel8/8/x86_64/rt/os',
      'content/dist/rhel8/8/x86_64/rt/source/SRPMS',
      'content/e6s/rhel8/8.10/x86_64/nfv/debug',
      'content/e6s/rhel8/8.10/x86_64/nfv/os',
      'content/e6s/rhel8/8.10/x86_64/nfv/source/SRPMS',
      'content/e6s/rhel8/8.10/x86_64/rt/debug',
      'content/e6s/rhel8/8.10/x86_64/rt/os',
      'content/e6s/rhel8/8.10/x86_64/rt/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'kernel-rt-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-core-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-debug-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-debug-core-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-debug-devel-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-debug-modules-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-debug-modules-extra-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-devel-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-modules-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-modules-extra-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  },
  {
    'release': '8',
    'repo_relative_urls': [
      'content/dist/rhel8/8.10/x86_64/nfv/debug',
      'content/dist/rhel8/8.10/x86_64/nfv/os',
      'content/dist/rhel8/8.10/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.6/x86_64/nfv/debug',
      'content/dist/rhel8/8.6/x86_64/nfv/os',
      'content/dist/rhel8/8.6/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.8/x86_64/nfv/debug',
      'content/dist/rhel8/8.8/x86_64/nfv/os',
      'content/dist/rhel8/8.8/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8.9/x86_64/nfv/debug',
      'content/dist/rhel8/8.9/x86_64/nfv/os',
      'content/dist/rhel8/8.9/x86_64/nfv/source/SRPMS',
      'content/dist/rhel8/8/x86_64/nfv/debug',
      'content/dist/rhel8/8/x86_64/nfv/os',
      'content/dist/rhel8/8/x86_64/nfv/source/SRPMS',
      'content/e6s/rhel8/8.10/x86_64/nfv/debug',
      'content/e6s/rhel8/8.10/x86_64/nfv/os',
      'content/e6s/rhel8/8.10/x86_64/nfv/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'kernel-rt-debug-kvm-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-rt-kvm-4.18.0-553.153.1.rt7.494.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var applicable_repo_urls = rhel_determine_applicable_repository_urls(constraints:constraints);
if(applicable_repo_urls == RHEL_REPOS_NO_OVERLAP_MESSAGE) exit(0, RHEL_REPO_NOT_ENABLED);

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 repo_relative_urls;
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;
  }

  if (!empty_or_null(constraint['repo_relative_urls'])) repo_relative_urls = constraint['repo_relative_urls'];

  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 &&
        rhel_decide_repo_relative_url_check(required_repo_url_list:repo_relative_urls) &&
        (applicable_repo_urls || (!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)
{
  var extra = NULL;
  if (isnull(applicable_repo_urls) || !applicable_repo_urls) extra = rpm_report_get() + redhat_report_repo_caveat();
  else extra = rpm_report_get();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : extra
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'kernel-rt / kernel-rt-core / kernel-rt-debug / kernel-rt-debug-core / etc');
}