CVE-2021-43854

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Summary

CVECVE-2021-43854
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-12-23 18:15:00 UTC
Updated2022-01-04 16:38:00 UTC
DescriptionNLTK (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.

Risk And Classification

Problem Types: CWE-400

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Nltk Nltk All All All All

References

ReferenceSourceLinkTags
Resolved serious ReDoS in PunktSentenceTokenizer by tomaarsen · Pull Request #2869 · nltk/nltk · GitHub MISC github.com
word_tokenize/EN hangs on incorrect strings · Issue #2866 · nltk/nltk · GitHub MISC github.com
Inefficient Regular Expression Complexity in nltk (word_tokenize, sent_tokenize) · Advisory · nltk/nltk · GitHub CONFIRM github.com
Resolved serious ReDoS in PunktSentenceTokenizer (#2869) · nltk/nltk@1405aad · GitHub MISC github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 184262 Debian Security Update for nltk (CVE-2021-43854)
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