Unity Linux 20.1050a Security Update: kernel (UTSA-2026-053301)

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

include('compat.inc');

if (description)
{
  script_id(343168);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/06");

  script_cve_id("CVE-2026-23340");

  script_name(english:"Unity Linux 20.1050a Security Update: kernel (UTSA-2026-053301)");

  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-2026-053301 advisory.

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

    net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs

    When shrinking the number of real tx queues,
    netif_set_real_num_tx_queues() calls qdisc_reset_all_tx_gt() to flush
    qdiscs for queues which will no longer be used.

    qdisc_reset_all_tx_gt() currently serializes qdisc_reset() with
    qdisc_lock(). However, for lockless qdiscs, the dequeue path is
    serialized by qdisc_run_begin/end() using qdisc->seqlock instead, so
    qdisc_reset() can run concurrently with __qdisc_run() and free skbs
    while they are still being dequeued, leading to UAF.

    This can easily be reproduced on e.g. virtio-net by imposing heavy
    traffic while frequently changing the number of queue pairs:

      iperf3 -ub0 -c $peer -t 0 &
      while :; do
        ethtool -L eth0 combined 1
        ethtool -L eth0 combined 2
      done

    With KASAN enabled, this leads to reports like:

      BUG: KASAN: slab-use-after-free in __qdisc_run+0x133f/0x1760
      ...
      Call Trace:
       <TASK>
       ...
       __qdisc_run+0x133f/0x1760
       __dev_queue_xmit+0x248f/0x3550
       ip_finish_output2+0xa42/0x2110
       ip_output+0x1a7/0x410
       ip_send_skb+0x2e6/0x480
       udp_send_skb+0xb0a/0x1590
       udp_sendmsg+0x13c9/0x1fc0
       ...
       </TASK>

      Allocated by task 1270 on cpu 5 at 44.558414s:
       ...
       alloc_skb_with_frags+0x84/0x7c0
       sock_alloc_send_pskb+0x69a/0x830
       __ip_append_data+0x1b86/0x48c0
       ip_make_skb+0x1e8/0x2b0
       udp_sendmsg+0x13a6/0x1fc0
       ...

      Freed by task 1306 on cpu 3 at 44.558445s:
       ...
       kmem_cache_free+0x117/0x5e0
       pfifo_fast_reset+0x14d/0x580
       qdisc_reset+0x9e/0x5f0
       netif_set_real_num_tx_queues+0x303/0x840
       virtnet_set_channels+0x1bf/0x260 [virtio_net]
       ethnl_set_channels+0x684/0xae0
       ethnl_default_set_doit+0x31a/0x890
       ...

    Serialize qdisc_reset_all_tx_gt() against the lockless dequeue path by
    taking qdisc->seqlock for TCQ_F_NOLOCK qdiscs, matching the
    serialization model already used by dev_reset_queue().

    Additionally clear QDISC_STATE_NON_EMPTY after reset so the qdisc state
    reflects an empty queue, avoiding needless re-scheduling.

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-2026-053301
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?8fbf1782");
  # https://lore.kernel.org/linux-cve-announce/2026032534-CVE-2026-23340-1aa9@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?ea159b78");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-23340");
  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:U/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:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-23340");

  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:"2026/03/25");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/06");

  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:"^(20.1050a)([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1050a', '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 && 'loongarch64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1050a',
    'pkgs': [
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'loongarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', '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');
}