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.
Advisories
Source ID Title
EUVD EUVD EUVD-2021-0148 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.
Github GHSA Github GHSA GHSA-f8m6-h2c7-8h9x Inefficient Regular Expression Complexity in nltk (word_tokenize, sent_tokenize)
Ubuntu USN Ubuntu USN USN-7365-1 NLTK vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

No history.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2024-08-04T04:10:16.281Z

Reserved: 2021-11-16T00:00:00

Link: CVE-2021-43854

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-12-23T18:15:07.327

Modified: 2024-11-21T06:29:56.200

Link: CVE-2021-43854

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.