Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : NLTK vulnerabilities (USN-8302-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8302-1. 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(316734);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/26");

  script_cve_id(
    "CVE-2026-0846",
    "CVE-2026-0847",
    "CVE-2026-0848",
    "CVE-2026-33230",
    "CVE-2026-33231",
    "CVE-2026-33236"
  );
  script_xref(name:"USN", value:"8302-1");

  script_name(english:"Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : NLTK vulnerabilities (USN-8302-1)");

  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 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages
installed that are affected by multiple vulnerabilities as referenced in the USN-8302-1 advisory.

    It was discovered that NLTK incorrectly validated file paths when opening files using the nltk.util
    module. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-0846)

    It was discovered that NLTK incorrectly validated file paths in multiple CorpusReader classes. An attacker
    could possibly use this issue to obtain sensitive information. (CVE-2026-0847)

    It was discovered that NLTK did not properly validate external Java archive files loaded by
    StanfordSegmenter. An attacker could possibly use this issue to execute arbitrary code. This issue only
    affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS.
    (CVE-2026-0848)

    It was discovered that NLTK's WordNet browser application incorrectly handled user-supplied input. An
    attacker could possibly use this issue to perform a cross-site scripting attack. (CVE-2026-33230)

    It was discovered that NLTK's WordNet browser application did not restrict access to the shutdown
    endpoint. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-33231)

    It was discovered that NLTK's downloader did not validate path attributes in remote XML index files. An
    attacker could possibly use this issue to create or overwrite arbitrary files. (CVE-2026-33236)

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-8302-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected python-nltk and / or python3-nltk packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/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:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-0847");

  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:"2026/03/04");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/26");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  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:"p-cpe:/a:canonical:ubuntu_linux:python-nltk");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-nltk");
  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_info.nasl", "ubuntu_pro_sub_detect.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 (! ('14.04' >< os_release || '16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release || '22.04' >< os_release || '24.04' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 14.04 / 16.04 / 18.04 / 20.04 / 22.04 / 24.04 / 26.04', '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 ubuntu_pro_detected = get_kb_item('Host/Ubuntu/Pro/Services/esm-apps');
ubuntu_pro_detected = !empty_or_null(ubuntu_pro_detected);

var pro_caveat_needed = FALSE;

var pkgs = [
    {'osver': '14.04', 'pkgname': 'python-nltk', 'pkgver': '2.0~b9-0ubuntu4.1~esm6', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '16.04', 'pkgname': 'python-nltk', 'pkgver': '3.1-1ubuntu0.1+esm4', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '16.04', 'pkgname': 'python3-nltk', 'pkgver': '3.1-1ubuntu0.1+esm4', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '18.04', 'pkgname': 'python-nltk', 'pkgver': '3.2.5-1ubuntu0.1+esm4', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-0848', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '18.04', 'pkgname': 'python3-nltk', 'pkgver': '3.2.5-1ubuntu0.1+esm4', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-0848', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '20.04', 'pkgname': 'python3-nltk', 'pkgver': '3.4.5-2ubuntu0.1~esm4', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-0848', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '22.04', 'pkgname': 'python3-nltk', 'pkgver': '3.7-1ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-0848', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '24.04', 'pkgname': 'python3-nltk', 'pkgver': '3.8.1-1ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-0848', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']},
    {'osver': '26.04', 'pkgname': 'python3-nltk', 'pkgver': '3.9.2-1ubuntu0.1~esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2026-0846', 'CVE-2026-0847', 'CVE-2026-0848', 'CVE-2026-33230', 'CVE-2026-33231', 'CVE-2026-33236']}
];

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

if (flag)
{
  var extra = '';
  if (pro_caveat_needed) {
    extra += 'NOTE: This vulnerability check contains fixes that apply to packages only \n';
    extra += 'available in Ubuntu ESM repositories. Access to these package security updates \n';
    extra += 'require an Ubuntu Pro subscription.\n\n';
  }
  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, 'python-nltk / python3-nltk');
}