AlmaLinux 9.2 [TuxCare] Security Update: bpftool / kernel / kernel-abi-stablelists / kernel-core / etc Multiple Vulnerabilities (ALMALINUX9.2:CLSA-2026:1778867412)

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

include('compat.inc');

if (description)
{
  script_id(360766);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/02");

  script_cve_id("CVE-2026-43503", "CVE-2026-46300");
  script_xref(name:"CLSA", value:"2026:1778867412");

  script_name(english:"AlmaLinux 9.2 [TuxCare] Security Update: bpftool / kernel / kernel-abi-stablelists / kernel-core / etc Multiple Vulnerabilities (ALMALINUX9.2:CLSA-2026:1778867412)");

  script_set_attribute(attribute:"synopsis", value:
"The AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The AlmaLinux 9.2 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare
ALMALINUX9.2:CLSA-2026:1778867412 advisory.

  - In the Linux kernel, the following vulnerability has been resolved: net: skbuff: propagate shared-frag
    marker through frag-transfer helpers Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail
    to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when moving frags from source to
    destination. __pskb_copy_fclone() defers the rest of the shinfo metadata to skb_copy_header() after
    copying frag descriptors, but that helper only carries over gso_{size,segs, type} and never touches
    skb_shinfo()->flags; skb_shift() moves frag descriptors directly and leaves flags untouched. As a result,
    the destination skb keeps a reference to the same externally-owned or page-cache-backed pages while
    reporting skb_has_shared_frag() as false. The mismatch is harmful in any in-place writer that uses
    skb_has_shared_frag() to decide whether shared pages must be detoured through skb_cow_data(). ESP input is
    one such writer (esp4.c, esp6.c), and a single nft 'dup to <local>' rule -- or any other nf_dup_ipv4() /
    xt_TEE caller -- is enough to land a pskb_copy()'d skb in esp_input() with the marker stripped, letting an
    unprivileged user write into the page cache of a root-owned read-only file via authencesn-ESN stray
    writes. Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors were actually moved from the
    source. skb_copy() and skb_copy_expand() share skb_copy_header() too but linearize all paged data into
    freshly allocated head storage and emerge with nr_frags == 0, so skb_has_shared_frag() returns false on
    its own; they need no change. The same omission exists in skb_gro_receive() and skb_gro_receive_list().
    The former moves the incoming skb's frag descriptors into the accumulator's last sub-skb via two paths (a
    direct frag-move loop and the head_frag + memcpy path); the latter chains the incoming skb whole onto p's
    frag_list. Downstream skb_segment() reads only skb_shinfo(p)->flags, and skb_segment_list() reuses each
    sub-skb's shinfo as the nskb -- both p and lp must carry the marker. The same omission also exists in
    tcp_clone_payload(), which builds an MTU probe skb by moving frag descriptors from skbs on sk_write_queue
    into a freshly allocated nskb. The helper falls into the same family and warrants the same fix for
    consistency; no TCP TX-side in-place writer is currently known to reach a user page through this gap, but
    a future consumer depending on the marker would regress silently. The same omission exists in
    skb_segment(): the per-iteration flag merge takes only head_skb's flag, and the inner switch that rebinds
    frag_skb to list_skb on head_skb-frags exhaustion does not fold the new frag_skb's flag into nskb. Fold
    frag_skb's flag at both sites so segments drawing frags from frag_list members carry the marker.
    (CVE-2026-43503)

  - In the Linux kernel, the following vulnerability has been resolved: net: skbuff: preserve shared-frag
    marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has
    SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed
    frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place
    writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned
    nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked
    skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags.
    Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not
    need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.
    (CVE-2026-46300)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/almalinux9.2esu/advisories/2026/clsa-2026_1778867412.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?1161ef9d");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1778867412");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory ALMALINUX9.2:CLSA-2026:1778867412.");
  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:'Sample Linux Priv Esc, DescriptionThis exploit module illustrates how a vulnerability could be exploitedin an linux command for priv esc.}');
  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:"2026/05/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/15");
  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:"Alma Linux 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/AlmaLinux/release", "Host/AlmaLinux/rpm-list", "Host/cpu");

  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) || 'AlmaLinux' >!< os_product) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
if (! preg(pattern:"^9.2([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 9.2', 'AlmaLinux ' + os_version);

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

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


var constraints = [
  {
    'release': '9',
    'sp': '2',
    'pkgs': [
      {'reference':'bpftool-7.0.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-abi-stablelists-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-core-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-cross-headers-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-core-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-devel-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-devel-matched-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-core-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-extra-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-internal-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-modules-partner-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-debug-uki-virt-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-devel-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-devel-matched-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-headers-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-ipaclones-internal-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-core-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-extra-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-internal-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-modules-partner-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-selftests-internal-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-tools-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-tools-libs-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-tools-libs-devel-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-uki-virt-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libbpf-1.0.0-2.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'i686', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'libbpf-1.0.0-2.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'libbpf-devel-1.0.0-2.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'i686', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'libbpf-devel-1.0.0-2.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'libbpf-static-1.0.0-2.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'i686', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'libbpf-static-1.0.0-2.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'perf-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-perf-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'rtla-5.14.0-284.1101.el9_2.tuxcare.7.els34', 'sp':'2', 'cpu':'x86_64', 'el_string':'el9_2', '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-abi-stablelists / kernel-core / etc');
}