Unity Linux 20.1050e Security Update: kernel (UTSA-2026-102016)

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

include('compat.inc');

if (description)
{
  script_id(338523);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/21");

  script_cve_id("CVE-2026-31788");

  script_name(english:"Unity Linux 20.1050e Security Update: kernel (UTSA-2026-102016)");

  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-2026-102016 advisory.

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

    xen/privcmd: restrict usage in unprivileged domU

    The Xen privcmd driver allows to issue arbitrary hypercalls from
    user space processes. This is normally no problem, as access is
    usually limited to root and the hypervisor will deny any hypercalls
    affecting other domains.

    In case the guest is booted using secure boot, however, the privcmd
    driver would be enabling a root user process to modify e.g. kernel
    memory contents, thus breaking the secure boot feature.

    The only known case where an unprivileged domU is really needing to
    use the privcmd driver is the case when it is acting as the device
    model for another guest. In this case all hypercalls issued via the
    privcmd driver will target that other guest.

    Fortunately the privcmd driver can already be locked down to allow
    only hypercalls targeting a specific domain, but this mode can be
    activated from user land only today.

    The target domain can be obtained from Xenstore, so when not running
    in dom0 restrict the privcmd driver to that target domain from the
    beginning, resolving the potential problem of breaking secure boot.

    This is XSA-482

    ---
    V2:
    - defer reading from Xenstore if Xenstore isn't ready yet (Jan Beulich)
    - wait in open() if target domain isn't known yet
    - issue message in case no target domain found (Jan Beulich)

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-2026-102016
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?0cc01349");
  # https://git.kernel.org/stable/c/1879319d790f7d57622cdc22807b60ea78b56b6d
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?2f82abd9");
  # https://git.kernel.org/stable/c/389bae9a4409934e8b8d4dbdaaf02a3ae71cf8e4
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?354fe31c");
  # https://git.kernel.org/stable/c/3ee5b9e3de4b8bdd74183d83205481c91a9effc8
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?9907bc2f");
  # https://git.kernel.org/stable/c/453b8fb68f3641fea970db88b7d9a153ed2a37e8
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?c9a223ea");
  # https://git.kernel.org/stable/c/4eb245ff0d33b618e097a2c23de5df56d4ad6969
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?36655603");
  # https://git.kernel.org/stable/c/78432d8f0372c71c518096395537fa12be7ff24e
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?11244665");
  # https://git.kernel.org/stable/c/87a803edb2ded911cb587c53bff179d2a2ed2a28
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?d6a20dba");
  # https://git.kernel.org/stable/c/cbede2e833da1893afbea9b3ff29b5dda23a4a91
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?57a71daf");
  # https://lore.kernel.org/linux-cve-announce/2026032548-CVE-2026-31788-032c@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?4a210c28");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-31788");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-31788");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:M/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:H/UI:N/S:C/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-2026-31788");

  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:"2026/08/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/21");

  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');
}