Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS / 26.10 : libXtst vulnerabilities (USN-8939-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8939-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(367752);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/21");

  script_cve_id("CVE-2016-7951", "CVE-2016-7952", "CVE-2026-94286");
  script_xref(name:"USN", value:"8939-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS / 26.10 : libXtst vulnerabilities (USN-8939-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS / 26.10 host has a package
installed that is affected by multiple vulnerabilities as referenced in the USN-8939-1 advisory.

    It was discovered that libXtst did not properly handle certain RECORD replies from the X server. A
    malicious X server could possibly use this issue to cause libXtst clients to crash, resulting in a denial
    of service. (CVE-2026-94286)

    Tobias Stoeckmann discovered that libXtst did not properly handle certain memory operations. A malicious X
    server could possibly use this issue to cause libXtst to access memory out of bounds, resulting in a
    denial of service. This issue only affected Ubuntu 16.04 LTS. (CVE-2016-7951)

    Tobias Stoeckmann discovered that libXtst did not properly handle certain replies from the X server. A
    malicious X server could possibly use this issue to cause libXtst to enter an infinite loop, resulting in
    a denial of service. This issue only affected Ubuntu 16.04 LTS. (CVE-2016-7952)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-8939-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected libxtst6 package.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/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-2016-7951");

  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:"2026/10/19");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/19");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/20");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libxtst6");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release || '22.04' >< os_release || '24.04' >< os_release || '26.04' >< os_release || '26.10' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04 / 18.04 / 20.04 / 22.04 / 24.04 / 26.04 / 26.10', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '16.04', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.2-1ubuntu0.1~esm1', 'cves': ['CVE-2016-7951', 'CVE-2016-7952', 'CVE-2026-94286']},
    {'osver': '18.04', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.3-1ubuntu0.18.04.1~esm1', 'cves': ['CVE-2026-94286']},
    {'osver': '20.04', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.3-1ubuntu0.20.04.1~esm1', 'cves': ['CVE-2026-94286']},
    {'osver': '22.04', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.3-1ubuntu0.22.04.1', 'cves': ['CVE-2026-94286']},
    {'osver': '24.04', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.3-1.1ubuntu0.1', 'cves': ['CVE-2026-94286']},
    {'osver': '26.04', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.5-1ubuntu0.1', 'cves': ['CVE-2026-94286']},
    {'osver': '26.10', 'pkgname': 'libxtst6', 'pkgver': '2:1.2.5-1ubuntu1', 'cves': ['CVE-2026-94286']}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libxtst6');
}