Unity Linux 20.1020e / 20.1050e / 20.1060e / 20.1070e Security Update: kernel (UTSA-2026-142477)

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

include('compat.inc');

if (description)
{
  script_id(370857);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/22");

  script_cve_id("CVE-2026-68398");

  script_name(english:"Unity Linux 20.1020e / 20.1050e / 20.1060e / 20.1070e Security Update: kernel (UTSA-2026-142477)");

  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-2026-142477 advisory.

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

    ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF

    pppol2tp_recv() runs in the L2TP UDP-encap softirq RX path:

     l2tp_udp_encap_recv() -> l2tp_recv_common() -> pppol2tp_recv()
       -> ppp_input(&po->chan)

    It runs under rcu_read_lock() holding only an l2tp_session reference and
    takes NO reference on the internal PPP channel (struct channel,
    chan->ppp) that ppp_input() dereferences.

    The pppox socket is SOCK_RCU_FREE, so 'po' and the embedded ppp_channel
    are RCU-safe.  But the internal struct channel is a separate allocation
    that ppp_release_channel() frees with a plain kfree():

     close(data socket) -> pppol2tp_release() -> pppox_unbind_sock()
       -> ppp_unregister_channel() -> ppp_release_channel() -> kfree(pch)

    For a channel that is bound (PPPIOCGCHAN) but not attached to a ppp unit
    (no PPPIOCCONNECT, pch->ppp == NULL) and not bridged, teardown skips
    both ppp_disconnect_channel()'s synchronize_net() and
    ppp_unbridge_channels()'s synchronize_rcu(), so the kfree() has no grace
    period.  rcu_read_lock() in pppol2tp_recv() does not protect against a
    plain kfree(), so an in-flight ppp_input() on one CPU can dereference
    the channel just freed by close() on another CPU.

    The bug is reachable by an unprivileged user.

    Defer the channel free to an RCU callback via call_rcu() so the grace
    period fences any in-flight ppp_input(). The disconnect and unbridge
    teardown paths already fence with synchronize_net()/synchronize_rcu();
    call_rcu() does the same here without stalling the close() path.

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-2026-142477
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?42715163");
  # https://lore.kernel.org/linux-cve-announce/2026081048-CVE-2026-68398-ca73@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?74819150");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-68398");
  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:POC/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:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-68398");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/10");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/22");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/22");

  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:"^(20.1020e|20.1050e|20.1060e|20.1070e)([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1020e / 20.1050e / 20.1060e / 20.1070e', '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 && 'sw_64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1020e',
    'pkgs': [
      {'reference':'kernel-4.19.90-2211.5.0.0178.68.uel20', 'sp':'1020e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.68.uel20', 'sp':'1020e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2211.5.0.0178.68.uel20', 'sp':'1020e', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  },
  {
    'release': '20',
    'sp': '1050e',
    'pkgs': [
      {'reference':'kernel-4.19.90-2305.1.0.0199.123.uel20', 'sp':'1050e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2305.1.0.0199.123.uel20', 'sp':'1050e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2305.1.0.0199.123.uel20', 'sp':'1050e', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  },
  {
    'release': '20',
    'sp': '1060e',
    'pkgs': [
      {'reference':'kernel-4.19.90-2311.4.0.0227.123.uel20', 'sp':'1060e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2311.4.0.0227.123.uel20', 'sp':'1060e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2311.4.0.0227.123.uel20', 'sp':'1060e', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  },
  {
    'release': '20',
    'sp': '1070e',
    'pkgs': [
      {'reference':'kernel-4.19.90-2601.1.0.0024.uel20', 'sp':'1070e', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2601.1.0.0024.uel20', 'sp':'1070e', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2601.1.0.0024.uel20', 'sp':'1070e', 'cpu':'sw_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.90-2601.1.0.0024.uel20', 'sp':'1070e', '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');
}