Vulnerability Details CVE-2026-80205
NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that accept user-supplied regular expressions without validation or timeout. Attackers can supply crafted regex patterns that cause catastrophic backtracking, resulting in indefinite CPU saturation and denial of service to all users of the Python process.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 30.9%
CVSS Severity
CVSS v3 Score 7.5
Products affected by CVE-2026-80205
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cpe:2.3:a:nltk:nltk:2.0.1
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cpe:2.3:a:nltk:nltk:2.0.3
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cpe:2.3:a:nltk:nltk:2.0.4
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cpe:2.3:a:nltk:nltk:3.0.0
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cpe:2.3:a:nltk:nltk:3.0.1
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cpe:2.3:a:nltk:nltk:3.0.2
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cpe:2.3:a:nltk:nltk:3.0.3
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cpe:2.3:a:nltk:nltk:3.0.4
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cpe:2.3:a:nltk:nltk:3.0.5
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cpe:2.3:a:nltk:nltk:3.2.1
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cpe:2.3:a:nltk:nltk:3.2.2
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cpe:2.3:a:nltk:nltk:3.2.3
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cpe:2.3:a:nltk:nltk:3.2.4
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cpe:2.3:a:nltk:nltk:3.2.5
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cpe:2.3:a:nltk:nltk:3.4.1
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cpe:2.3:a:nltk:nltk:3.4.3
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cpe:2.3:a:nltk:nltk:3.4.4
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cpe:2.3:a:nltk:nltk:3.4.5
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cpe:2.3:a:nltk:nltk:3.6.1
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cpe:2.3:a:nltk:nltk:3.6.2
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cpe:2.3:a:nltk:nltk:3.6.3
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cpe:2.3:a:nltk:nltk:3.6.4
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cpe:2.3:a:nltk:nltk:3.6.5
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cpe:2.3:a:nltk:nltk:3.6.6
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cpe:2.3:a:nltk:nltk:3.6.7
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cpe:2.3:a:nltk:nltk:3.8.1
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cpe:2.3:a:nltk:nltk:3.9.1
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cpe:2.3:a:nltk:nltk:3.9.2
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cpe:2.3:a:nltk:nltk:3.9.3
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cpe:2.3:a:nltk:nltk:3.9.4