CVE-2026-81725
Low · 3.7CVSS
3.7
EPSS
0.4%
Published
Aug 27, 2026
CISA due date
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The record
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.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
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