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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References
History
Thu, 27 Aug 2026 16:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | NLTK before 3.10.3 Regular Expression Denial of Service via Pl196xCorpusReader | |
| First Time appeared |
Nltk
Nltk nltk |
|
| Weaknesses | CWE-400 | |
| CPEs | cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Nltk
Nltk nltk |
|
| References |
| |
| Metrics |
cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-08-27T14:51:18.082Z
Reserved: 2026-08-27T11:15:29.420Z
Link: CVE-2026-81725
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Redhat
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Weaknesses