Unity Linux 20.1050e Security Update: kernel (UTSA-2026-102133)

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

include('compat.inc');

if (description)
{
  script_id(337320);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/18");

  script_cve_id("CVE-2026-43361");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-102133)");

  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-2026-102133 advisory.

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

    btrfs: fix transaction abort when snapshotting received subvolumes

    Currently a user can trigger a transaction abort by snapshotting a
    previously received snapshot a bunch of times until we reach a
    BTRFS_UUID_KEY_RECEIVED_SUBVOL item overflow (the maximum item size we
    can store in a leaf). This is very likely not common in practice, but
    if it happens, it turns the filesystem into RO mode. The snapshot, send
    and set_received_subvol and subvol_setflags (used by receive) don't
    require CAP_SYS_ADMIN, just inode_owner_or_capable(). A malicious user
    could use this to turn a filesystem into RO mode and disrupt a system.

    Reproducer script:

      $ cat test.sh
      #!/bin/bash

      DEV=/dev/sdi
      MNT=/mnt/sdi

      # Use smallest node size to make the test faster.
      mkfs.btrfs -f --nodesize 4K $DEV
      mount $DEV $MNT

      # Create a subvolume and set it to RO so that it can be used for send.
      btrfs subvolume create $MNT/sv
      touch $MNT/sv/foo
      btrfs property set $MNT/sv ro true

      # Send and receive the subvolume into snaps/sv.
      mkdir $MNT/snaps
      btrfs send $MNT/sv | btrfs receive $MNT/snaps

      # Now snapshot the received subvolume, which has a received_uuid, a
      # lot of times to trigger the leaf overflow.
      total=500
      for ((i = 1; i <= $total; i++)); do
          echo -ne  Creating snapshot $i/$total
          btrfs subvolume snapshot -r $MNT/snaps/sv $MNT/snaps/sv_$i > /dev/null
      done
      echo

      umount $MNT

    When running the test:

      $ ./test.sh
      (...)
      Create subvolume '/mnt/sdi/sv'
      At subvol /mnt/sdi/sv
      At subvol sv
      Creating snapshot 496/500ERROR: Could not create subvolume: Value too large for defined data type
      Creating snapshot 497/500ERROR: Could not create subvolume: Read-only file system
      Creating snapshot 498/500ERROR: Could not create subvolume: Read-only file system
      Creating snapshot 499/500ERROR: Could not create subvolume: Read-only file system
      Creating snapshot 500/500ERROR: Could not create subvolume: Read-only file system

    And in dmesg/syslog:

      $ dmesg
      (...)
      [251067.627338] BTRFS warning (device sdi): insert uuid item failed -75 (0x4628b21c4ac8d898,
    0x2598bee2b1515c91) type 252!
      [251067.629212] ------------[ cut here ]------------
      [251067.630033] BTRFS: Transaction aborted (error -75)
      [251067.630871] WARNING: fs/btrfs/transaction.c:1907 at create_pending_snapshot.cold+0x52/0x465 [btrfs],
    CPU#10: btrfs/615235
      [251067.632851] Modules linked in: btrfs dm_zero (...)
      [251067.644071] CPU: 10 UID: 0 PID: 615235 Comm: btrfs Tainted: G        W           6.19.0-rc8-btrfs-
    next-225+ #1 PREEMPT(full)
      [251067.646165] Tainted: [W]=WARN
      [251067.646733] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
    rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
      [251067.648735] RIP: 0010:create_pending_snapshot.cold+0x55/0x465 [btrfs]
      [251067.649984] Code: f0 48 0f (...)
      [251067.653313] RSP: 0018:ffffce644908fae8 EFLAGS: 00010292
      [251067.653987] RAX: 00000000ffffff01 RBX: ffff8e5639e63a80 RCX: 00000000ffffffd3
      [251067.655042] RDX: ffff8e53faa76b00 RSI: 00000000ffffffb5 RDI: ffffffffc0919750
      [251067.656077] RBP: ffffce644908fbd8 R08: 0000000000000000 R09: ffffce644908f820
      [251067.657068] R10: ffff8e5adc1fffa8 R11: 0000000000000003 R12: ffff8e53c0431bd0
      [251067.658050] R13: ffff8e5414593600 R14: ffff8e55efafd000 R15: 00000000ffffffb5
      [251067.659019] FS:  00007f2a4944b3c0(0000) GS:ffff8e5b27dae000(0000) knlGS:0000000000000000
      [251067.660115] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [251067.660943] CR2: 00007ffc5aa57898 CR3: 00000005813a2003 CR4: 0000000000370ef0
      [251067.661972] Call Trace:
      [251067.662292]  <TASK>
      [251067.662653]  create_pending_snapshots+0x97/0xc0 [btrfs]
      [251067.663413]  btrfs_commit_transaction+0x26e/0xc00 [btrfs]
      [251067.664257]  ? btrfs_qgroup_convert_reserved_meta+0x35/0x390 [btrfs]
      [251067.665238]  ? _raw_spin_unlock+0x15/0x30
      [251067.665837]  ? record_root_
    ---truncated---

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-2026-102133
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?86b380d7");
  # https://lore.kernel.org/linux-cve-announce/2026050826-CVE-2026-43361-ffe2@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?6ce618a1");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-43361");
  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-2026-43361");

  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:"2026/05/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/18");

  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-4.19.90-2211.5.0.0178.67.uel20', 'sp':'1050e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.67.uel20', 'sp':'1050e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.67.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');
}