CentOS Linux 8 [TuxCare] Security Update: bpftool / kernel / kernel-core / kernel-cross-headers / etc (CENTOS-STREAM8:CLSA-2026:1778260978)

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

include('compat.inc');

if (description)
{
  script_id(361296);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/02");

  script_cve_id("CVE-2026-43284");
  script_xref(name:"CLSA", value:"2026:1778260978");

  script_name(english:"CentOS Linux 8 [TuxCare] Security Update: bpftool / kernel / kernel-core / kernel-cross-headers / etc (CENTOS-STREAM8:CLSA-2026:1778260978)");

  script_set_attribute(attribute:"synopsis", value:
"The CentOS Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The CentOS Linux 8 host has packages installed that are affected by a vulnerability as referenced in the TuxCare CENTOS-
STREAM8:CLSA-2026:1778260978 advisory.

  - In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: avoid in-place decrypt on
    shared skb frags MSG_SPLICE_PAGES can attach pages from a pipe directly to an skb. TCP marks such skbs
    with SKBFL_SHARED_FRAG after skb_splice_from_iter(), so later paths that may modify packet data can first
    make a private copy. The IPv4/IPv6 datagram append paths did not set this flag when splicing pages into
    UDP skbs. That leaves an ESP-in-UDP packet made from shared pipe pages looking like an ordinary uncloned
    nonlinear skb. ESP input then takes the no-COW fast path for uncloned skbs without a frag_list and
    decrypts in place over data that is not owned privately by the skb. Mark IPv4/IPv6 datagram splice frags
    with SKBFL_SHARED_FRAG, matching TCP. Also make ESP input fall back to skb_cow_data() when the flag is
    present, so ESP does not decrypt externally backed frags in place. Private nonlinear skb frags still use
    the existing fast path. This intentionally does not change ESP output. In esp_output_head(), the path that
    appends the ESP trailer to existing skb tailroom without calling skb_cow_data() is not reachable for
    nonlinear skbs: skb_tailroom() returns zero when skb->data_len is nonzero, while ESP tailen is positive.
    Thus ESP output will either use the separate destination-frag path or fall back to skb_cow_data().
    (CVE-2026-43284)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/centos-stream8els/advisories/2026/clsa-2026_1778260978.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?f4b40568");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1778260978");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory CENTOS-STREAM8:CLSA-2026:1778260978.");
  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-2026-43284");

  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:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/01");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CentOS 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/OS/extended-third-party", "Host/local_checks_enabled", "Host/CentOS/release", "Host/CentOS/rpm-list");

  exit(0);
}
include('rpm2.inc');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (empty_or_null(third_party_support) || third_party_support != 'TuxCare') exit(0, 'TuxCare support not enabled.');

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) || 'CentOS Linux' >!< os_product) audit(AUDIT_OS_NOT, 'CentOS Linux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'CentOS Linux');
if (! preg(pattern:"^8([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'CentOS Linux 8', 'CentOS Linux ' + os_version);

if (!get_kb_item('Host/CentOS/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) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'CentOS Linux', cpu);


var constraints = [
  {
    'release': '8',
    'pkgs': [
      {'reference':'bpftool-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-core-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-cross-headers-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-core-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-devel-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-extra-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-internal-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-devel-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-headers-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-ipaclones-internal-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-extra-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-internal-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-selftests-internal-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-tools-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-tools-libs-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-tools-libs-devel-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'perf-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-perf-4.18.0-553.6.1.el8_10.tuxcare.els18', 'cpu':'x86_64', 'el_string':'el8_10', '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_WARNING,
      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, 'bpftool / kernel / kernel-core / kernel-cross-headers / etc');
}