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PYSEC-2026-3752

Quick fix

PYSEC-2026-3752 — nltk: upgrade to the fixed version with the command below.

pip install --upgrade 'nltk>=3.10.3'

Details

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.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/nltk
Introduced in: 0Fixed in: 3.10.3
Fixpip install --upgrade 'nltk>=3.10.3'

References