Advisories

NLTK before 3.10.3 Regular Expression Denial of Service via Pl196xCorpusReader

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severity
low
date
Affecting
  • nltk >= 0, < 3.10.3

CWE
  • CWE-400 Uncontrolled Resource Consumption
CVSS
6.3
CVSS V4 Vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Description
NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption by supplying malformed TEI blocks with many unmatched opening tags. Attackers can exploit lazy regex patterns in the read_block method through public APIs like words() and tagged_words() to force repeated rescans and achieve near-quadratic runtime growth.

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