Unity Linux 20.1050e Security Update: kernel (UTSA-2026-021650)

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

include('compat.inc');

if (description)
{
  script_id(315905);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/20");

  script_cve_id("CVE-2024-43853");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-021650)");

  script_set_attribute(attribute:"synopsis", value:
"The Unity Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the
UTSA-2026-021650 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    cgroup/cpuset: Prevent UAF in proc_cpuset_show()

    An UAF can happen when /proc/cpuset is read as reported in [1].

    This can be reproduced by the following methods:
    1.add an mdelay(1000) before acquiring the cgroup_lock In the
     cgroup_path_ns function.
    2.$cat /proc/<pid>/cpuset   repeatly.
    3.$mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset/
    $umount /sys/fs/cgroup/cpuset/   repeatly.

    The race that cause this bug can be shown as below:

    (umount)                |       (cat /proc/<pid>/cpuset)
    css_release             |       proc_cpuset_show
    css_release_work_fn     |       css = task_get_css(tsk, cpuset_cgrp_id);
    css_free_rwork_fn       |       cgroup_path_ns(css->cgroup, ...);
    cgroup_destroy_root     |       mutex_lock(&cgroup_mutex);
    rebind_subsystems       |
    cgroup_free_root        |
                            |       // cgrp was freed, UAF
                            |       cgroup_path_ns_locked(cgrp,..);

    When the cpuset is initialized, the root node top_cpuset.css.cgrp
    will point to &cgrp_dfl_root.cgrp. In cgroup v1, the mount operation will
    allocate cgroup_root, and top_cpuset.css.cgrp will point to the allocated
    &cgroup_root.cgrp. When the umount operation is executed,
    top_cpuset.css.cgrp will be rebound to &cgrp_dfl_root.cgrp.

    The problem is that when rebinding to cgrp_dfl_root, there are cases
    where the cgroup_root allocated by setting up the root for cgroup v1
    is cached. This could lead to a Use-After-Free (UAF) if it is
    subsequently freed. The descendant cgroups of cgroup v1 can only be
    freed after the css is released. However, the css of the root will never
    be released, yet the cgroup_root should be freed when it is unmounted.
    This means that obtaining a reference to the css of the root does
    not guarantee that css.cgrp->root will not be freed.

    Fix this problem by using rcu_read_lock in proc_cpuset_show().
    As cgroup_root is kfree_rcu after commit d23b5c577715
    (cgroup: Make operations on the cgroup root_list RCU safe),
    css->cgroup won't be freed during the critical section.
    To call cgroup_path_ns_locked, css_set_lock is needed, so it is safe to
    replace task_get_css with task_css.

    [1] https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd

Tenable has extracted the preceding description block directly from the Unity 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.");
  # https://src.uniontech.com/#/security_advisory_detail?utsa_id=UTSA-2026-021650
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?b301ea9b");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2024-43853");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/I:N/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:L/PR:L/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2024-43853");

  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:"2024/08/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/20");

  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:"Unity 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/local_checks_enabled", "Host/UOS-Server/release", "Host/UOS-Server/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm2.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) || 'UOS Server' >!< os_product) audit(AUDIT_OS_NOT, 'UOS Server');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'UOS Server');
if (! preg(pattern:"^20.1050e([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1050e', 'UOS Server ' + os_version);

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

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('aarch64' >!< cpu && 'amd64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1050e',
    'pkgs': [
      {'reference':'kernel-4.19.90-2211.5.0.0178.56.uel20', 'sp':'1050e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.56.uel20', 'sp':'1050e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.56.uel20', 'sp':'1050e', 'cpu':'x86_64', '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, 'kernel');
}