Vulnerabilities > CVE-2019-14751 - Path Traversal vulnerability in Nltk

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
HIGH
Availability impact
NONE
network
low complexity
nltk
CWE-22
nessus
NVD
Published: 2019-08-22
Updated: 2023-11-07

Summary

NLTK Downloader before 3.4.5 is vulnerable to a directory traversal, allowing attackers to write arbitrary files via a ../ (dot dot slash) in an NLTK package (ZIP archive) that is mishandled during extraction.

Vulnerable Configurations

Part Description Count
Application
Nltk
28

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Relative Path Traversal
    An attacker exploits a weakness in input validation on the target by supplying a specially constructed path utilizing dot and slash characters for the purpose of obtaining access to arbitrary files or resources. An attacker modifies a known path on the target in order to reach material that is not available through intended channels. These attacks normally involve adding additional path separators (/ or \) and/or dots (.), or encodings thereof, in various combinations in order to reach parent directories or entirely separate trees of the target's directory structure.
  • Directory Traversal
    An attacker with access to file system resources, either directly or via application logic, will use various file path specification or navigation mechanisms such as ".." in path strings and absolute paths to extend their range of access to inappropriate areas of the file system. The attacker attempts to either explore the file system for recon purposes or access directories and files that are intended to be restricted from their access. Exploring the file system can be achieved through constructing paths presented to directory listing programs, such as "ls" and 'dir', or through specially crafted programs that attempt to explore the file system. The attacker engaging in this type of activity is searching for information that can be used later in a more exploitive attack. Access to restricted directories or files can be achieved through modification of path references utilized by system applications.
  • File System Function Injection, Content Based
    An attack of this type exploits the host's trust in executing remote content including binary files. The files are poisoned with a malicious payload (targeting the file systems accessible by the target software) by the attacker and may be passed through standard channels such as via email, and standard web content like PDF and multimedia files. The attacker exploits known vulnerabilities or handling routines in the target processes. Vulnerabilities of this type have been found in a wide variety of commercial applications from Microsoft Office to Adobe Acrobat and Apple Safari web browser. When the attacker knows the standard handling routines and can identify vulnerabilities and entry points they can be exploited by otherwise seemingly normal content. Once the attack is executed, the attackers' program can access relative directories such as C:\Program Files or other standard system directories to launch further attacks. In a worst case scenario, these programs are combined with other propagation logic and work as a virus.
  • Using Slashes and URL Encoding Combined to Bypass Validation Logic
    This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple way of encoding an URL and abuse the interpretation of the URL. An URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
  • Manipulating Input to File System Calls
    An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

Nessus

  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-4106-1.NASL
    descriptionMike Salvatore discovered that NLTK mishandled crafted ZIP archives during extraction. A remote attacker could use this vulnerability to write arbitrary files to the filesystem. Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-01
    modified2020-06-02
    plugin id128049
    published2019-08-21
    reporterUbuntu Security Notice (C) 2019-2020 Canonical, Inc. / NASL script (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/128049
    titleUbuntu 16.04 LTS / 18.04 LTS / 19.04 : NLTK vulnerability (USN-4106-1)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4106-1. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include("compat.inc");

if (description)
{
  script_id(128049);
  script_version("1.4");
  script_cvs_date("Date: 2020/01/02");

  script_cve_id("CVE-2019-14751");
  script_xref(name:"USN", value:"4106-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 19.04 : NLTK vulnerability (USN-4106-1)");
  script_summary(english:"Checks dpkg output for updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote Ubuntu host is missing one or more security-related
patches."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Mike Salvatore discovered that NLTK mishandled crafted ZIP archives
during extraction. A remote attacker could use this vulnerability to
write arbitrary files to the filesystem.

Note that Tenable Network Security has extracted the preceding
description block directly from the Ubuntu security advisory. Tenable
has attempted to automatically clean and format it as much as possible
without introducing additional issues."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://usn.ubuntu.com/4106-1/"
  );
  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:N/I:P/A:N");
  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:N/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04");
  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:19.04");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/08/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/08/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/08/21");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2019-2020 Canonical, Inc. / NASL script (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Ubuntu Local Security Checks");

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

  exit(0);
}


include("audit.inc");
include("ubuntu.inc");
include("misc_func.inc");

if ( ! get_kb_item("Host/local_checks_enabled") ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/Ubuntu/release");
if ( isnull(release) ) audit(AUDIT_OS_NOT, "Ubuntu");
release = chomp(release);
if (! preg(pattern:"^(16\.04|18\.04|19\.04)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 16.04 / 18.04 / 19.04", "Ubuntu " + release);
if ( ! get_kb_item("Host/Debian/dpkg-l") ) audit(AUDIT_PACKAGE_LIST_MISSING);

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

flag = 0;

if (ubuntu_check(osver:"16.04", pkgname:"python-nltk", pkgver:"3.1-1ubuntu0.1")) flag++;
if (ubuntu_check(osver:"16.04", pkgname:"python3-nltk", pkgver:"3.1-1ubuntu0.1")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"python-nltk", pkgver:"3.2.5-1ubuntu0.1")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"python3-nltk", pkgver:"3.2.5-1ubuntu0.1")) flag++;
if (ubuntu_check(osver:"19.04", pkgname:"python-nltk", pkgver:"3.4-1ubuntu0.1")) flag++;
if (ubuntu_check(osver:"19.04", pkgname:"python3-nltk", pkgver:"3.4-1ubuntu0.1")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "python-nltk / python3-nltk");
}
  • NASL familySuSE Local Security Checks
    NASL idOPENSUSE-2020-436.NASL
    descriptionThis update for python-nltk fixes the following issues : Update to 3.4.5 (boo#1146427, CVE-2019-14751) : - CVE-2019-14751: Fixed Zip slip vulnerability in downloader for the unlikely situation where a user configures their downloader to use a compromised server (boo#1146427) Update to 3.4.4 : - fix bug in plot function (probability.py) - add improved PanLex Swadesh corpus reader - add Text.generate() - add QuadgramAssocMeasures - add SSP to tokenizers - return confidence of best tag from AveragedPerceptron - make plot methods return Axes objects - don
    last seen2020-04-07
    modified2020-04-02
    plugin id135162
    published2020-04-02
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/135162
    titleopenSUSE Security Update : python-nltk (openSUSE-2020-436)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from openSUSE Security Update openSUSE-2020-436.
#
# The text description of this plugin is (C) SUSE LLC.
#

include("compat.inc");

if (description)
{
  script_id(135162);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/04/06");

  script_cve_id("CVE-2019-14751");

  script_name(english:"openSUSE Security Update : python-nltk (openSUSE-2020-436)");
  script_summary(english:"Check for the openSUSE-2020-436 patch");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote openSUSE host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"This update for python-nltk fixes the following issues :

Update to 3.4.5 (boo#1146427, CVE-2019-14751) :

  - CVE-2019-14751: Fixed Zip slip vulnerability in
    downloader for the unlikely situation where a user
    configures their downloader to use a compromised server
    (boo#1146427)

Update to 3.4.4 :

  - fix bug in plot function (probability.py)

  - add improved PanLex Swadesh corpus reader

  - add Text.generate()

  - add QuadgramAssocMeasures

  - add SSP to tokenizers

  - return confidence of best tag from AveragedPerceptron

  - make plot methods return Axes objects

  - don't require list arguments to
    PositiveNaiveBayesClassifier.train

  - fix Tree classes to work with native Python copy library

  - fix inconsistency for NomBank

  - fix random seeding in LanguageModel.generate

  - fix ConditionalFreqDist mutation on tabulate/plot call

  - fix broken links in documentation

  - fix misc Wordnet issues

  - update installation instructions

Version update to 3.4.1 :

  - add chomsky_normal_form for CFGs

  - add meteor score

  - add minimum edit/Levenshtein distance based alignment
    function

  - allow access to collocation list via
    text.collocation_list()

  - support corenlp server options

  - drop support for Python 3.4

  - other minor fixes

Update to v3.4 :

  - Support Python 3.7

  - New Language Modeling package

  - Cistem Stemmer for German

  - Support Russian National Corpus incl POS tag model

  - Krippendorf Alpha inter-rater reliability test

  - Comprehensive code clean-ups

  - Switch continuous integration from Jenkins to Travis

Updated to v3.3 :

  - Support Python 3.6

  - New interface to CoreNLP

  - Support synset retrieval by sense key

  - Minor fixes to CoNLL Corpus Reader

  - AlignedSent

  - Fixed minor inconsistencies in APIs and API
    documentation

  - Better conformance to PEP8

  - Drop Moses Tokenizer (incompatible license)"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.opensuse.org/show_bug.cgi?id=1146427"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected python-nltk packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  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:N/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:python2-nltk");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:python3-nltk");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:opensuse:15.1");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/08/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/03/31");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/04/02");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"SuSE Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/SuSE/release", "Host/SuSE/rpm-list");

  exit(0);
}


include("audit.inc");
include("global_settings.inc");
include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/SuSE/release");
if (isnull(release) || release =~ "^(SLED|SLES)") audit(AUDIT_OS_NOT, "openSUSE");
if (release !~ "^(SUSE15\.1)$") audit(AUDIT_OS_RELEASE_NOT, "openSUSE", "15.1", release);
if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);



flag = 0;

if ( rpm_check(release:"SUSE15.1", reference:"python2-nltk-3.4.5-lp151.4.3.1") ) flag++;
if ( rpm_check(release:"SUSE15.1", reference:"python3-nltk-3.4.5-lp151.4.3.1") ) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
  else security_warning(0);
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "python2-nltk / python3-nltk");
}
  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2020-0F785235BB.NASL
    descriptionUpdate to latest stable release to fix CVE-2019-14751. Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-04-03
    modified2020-03-30
    plugin id134985
    published2020-03-30
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/134985
    titleFedora 31 : 1:python-nltk (2020-0f785235bb)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Fedora Security Advisory FEDORA-2020-0f785235bb.
#

include("compat.inc");

if (description)
{
  script_id(134985);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/04/02");

  script_cve_id("CVE-2019-14751");
  script_xref(name:"FEDORA", value:"2020-0f785235bb");

  script_name(english:"Fedora 31 : 1:python-nltk (2020-0f785235bb)");
  script_summary(english:"Checks rpm output for the updated package.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Fedora host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Update to latest stable release to fix CVE-2019-14751.

Note that Tenable Network Security has extracted the preceding
description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as
possible without introducing additional issues."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bodhi.fedoraproject.org/updates/FEDORA-2020-0f785235bb"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected 1:python-nltk package."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  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:N/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:1:python-nltk");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:31");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/08/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/03/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/03/30");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Fedora Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list");

  exit(0);
}


include("audit.inc");
include("global_settings.inc");
include("rpm.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/RedHat/release");
if (isnull(release) || "Fedora" >!< release) audit(AUDIT_OS_NOT, "Fedora");
os_ver = pregmatch(pattern: "Fedora.*release ([0-9]+)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Fedora");
os_ver = os_ver[1];
if (! preg(pattern:"^31([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 31", "Fedora " + os_ver);

if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);


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


flag = 0;
if (rpm_check(release:"FC31", reference:"python-nltk-3.4.5-2.fc31", epoch:"1")) flag++;


if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "1:python-nltk");
}

References