CVE-2021-43854 (High) detected in nltk-3.4.5.zip

[mend-bolt-for-github]

CVE-2021-43854 - High Severity Vulnerability

Vulnerable Library - nltk-3.4.5.zip

Natural Language Toolkit

Library home page: https://files.pythonhosted.org/packages/f6/1d/d925cfb4f324ede997f6d47bea4d9babba51b49e87a767c170b77005889d/nltk-3.4.5.zip

Path to dependency file: /requirements.txt

Path to vulnerable library: /requirements.txt,/datastore

Dependency Hierarchy:

• ❌ nltk-3.4.5.zip (Vulnerable Library)

Found in HEAD commit: a835daa282bf10ee52224e097ff04df34ab7852d

Found in base branch: develop

Vulnerability Details

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Versions prior to 3.6.5 are vulnerable to regular expression denial of service (ReDoS) attacks. The vulnerability is present in PunktSentenceTokenizer, sent_tokenize and word_tokenize. Any users of this class, or these two functions, are vulnerable to the ReDoS attack. In short, a specifically crafted long input to any of these vulnerable functions will cause them to take a significant amount of execution time. If your program relies on any of the vulnerable functions for tokenizing unpredictable user input, then we would strongly recommend upgrading to a version of NLTK without the vulnerability. For users unable to upgrade the execution time can be bounded by limiting the maximum length of an input to any of the vulnerable functions. Our recommendation is to implement such a limit.

Publish Date: 2021-12-23

URL: CVE-2021-43854

CVSS 3 Score Details (7.5)

Base Score Metrics:

• Exploitability Metrics:
  • Attack Vector: Network
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: None
  • Scope: Unchanged
• Impact Metrics:
  • Confidentiality Impact: None
  • Integrity Impact: None
  • Availability Impact: High

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Origin: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-43854

Release Date: 2021-12-23

Fix Resolution: 3.6.6

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