PT-2026-82079 · Pypi · Nltk

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CVE-2026-80205

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Published

2026-08-26

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Updated

2026-09-08

CVSS v4.0

8.7

High

VectorAV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.0
Description An issue exists where the findall() functions within the Text and TokenSearcher classes accept user-supplied regular expressions without validation or timeout. This can lead to catastrophic backtracking—a condition where the regex engine takes an exponential amount of time to process a string—resulting in indefinite CPU saturation and denial of service for all users of the Python process.
Recommendations Update NLTK to version 3.10.0 or later. As a temporary mitigation, restrict the use of the findall() function in Text and TokenSearcher when processing untrusted user input.

Exploit

Fix

DoS

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Weakness Enumeration

Related Identifiers

CVE-2026-80205
GHSA-2RRW-HPQM-36PV
GHSA-RRV8-H7P8-RX55
PYSEC-2026-3750

Affected Products

Nltk