Unity Linux 20.1050a Security Update: kernel (UTSA-2026-098803)

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

include('compat.inc');

if (description)
{
  script_id(340220);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/28");

  script_cve_id("CVE-2026-23406");

  script_name(english:"Unity Linux 20.1050a Security Update: kernel (UTSA-2026-098803)");

  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-2026-098803 advisory.

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

    apparmor: fix side-effect bug in match_char() macro usage

    The match_char() macro evaluates its character parameter multiple
    times when traversing differential encoding chains. When invoked
    with *str++, the string pointer advances on each iteration of the
    inner do-while loop, causing the DFA to check different characters
    at each iteration and therefore skip input characters.
    This results in out-of-bounds reads when the pointer advances past
    the input buffer boundary.

    [   94.984676] ==================================================================
    [   94.985301] BUG: KASAN: slab-out-of-bounds in aa_dfa_match+0x5ae/0x760
    [   94.985655] Read of size 1 at addr ffff888100342000 by task file/976

    [   94.986319] CPU: 7 UID: 1000 PID: 976 Comm: file Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy)
    [   94.986322] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
    [   94.986329] Call Trace:
    [   94.986341]  <TASK>
    [   94.986347]  dump_stack_lvl+0x5e/0x80
    [   94.986374]  print_report+0xc8/0x270
    [   94.986384]  ? aa_dfa_match+0x5ae/0x760
    [   94.986388]  kasan_report+0x118/0x150
    [   94.986401]  ? aa_dfa_match+0x5ae/0x760
    [   94.986405]  aa_dfa_match+0x5ae/0x760
    [   94.986408]  __aa_path_perm+0x131/0x400
    [   94.986418]  aa_path_perm+0x219/0x2f0
    [   94.986424]  apparmor_file_open+0x345/0x570
    [   94.986431]  security_file_open+0x5c/0x140
    [   94.986442]  do_dentry_open+0x2f6/0x1120
    [   94.986450]  vfs_open+0x38/0x2b0
    [   94.986453]  ? may_open+0x1e2/0x2b0
    [   94.986466]  path_openat+0x231b/0x2b30
    [   94.986469]  ? __x64_sys_openat+0xf8/0x130
    [   94.986477]  do_file_open+0x19d/0x360
    [   94.986487]  do_sys_openat2+0x98/0x100
    [   94.986491]  __x64_sys_openat+0xf8/0x130
    [   94.986499]  do_syscall_64+0x8e/0x660
    [   94.986515]  ? count_memcg_events+0x15f/0x3c0
    [   94.986526]  ? srso_alias_return_thunk+0x5/0xfbef5
    [   94.986540]  ? handle_mm_fault+0x1639/0x1ef0
    [   94.986551]  ? vma_start_read+0xf0/0x320
    [   94.986558]  ? srso_alias_return_thunk+0x5/0xfbef5
    [   94.986561]  ? srso_alias_return_thunk+0x5/0xfbef5
    [   94.986563]  ? fpregs_assert_state_consistent+0x50/0xe0
    [   94.986572]  ? srso_alias_return_thunk+0x5/0xfbef5
    [   94.986574]  ? arch_exit_to_user_mode_prepare+0x9/0xb0
    [   94.986587]  ? srso_alias_return_thunk+0x5/0xfbef5
    [   94.986588]  ? irqentry_exit+0x3c/0x590
    [   94.986595]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
    [   94.986597] RIP: 0033:0x7fda4a79c3ea

    Fix by extracting the character value before invoking match_char,
    ensuring single evaluation per outer loop.

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-2026-098803
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7ed4d91e");
  # https://lore.kernel.org/linux-cve-announce/2026040112-CVE-2026-23406-0cb2@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7e34e03b");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-23406");
  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-2026-23406");

  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:"2026/04/01");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/26");

  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');
}