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Vulnerability record · CVE-2026-81726 · published 27 August 2026

CVE-2026-81726: Nltk vulnerability

Nltk · Nltk

NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on caller-controlled paths. Attackers can read or write files outside allowed sandbox roots through TransitionParser, AveragedPerceptron, PerceptronTagger, and maxent parameter APIs when pathsec is enabled.

8.3 CVSS 4.0 High EPSS 0.34% · top 75.2% CWE-73 · CWE-73
8.3CVSS 4.0 base score
0.34%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 2 tagged exploit
31 Aug 2026Last modified by NVD

Description

NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on caller-controlled paths. Attackers can read or write files outside allowed sandbox roots through TransitionParser, AveragedPerceptron, PerceptronTagger, and maxent parameter APIs when pathsec is enabled.

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:L/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/nltk/nltk/security/advisories/GHSA-8mgp-746c-j5xp ExploitVendor Advisory
https://www.vulncheck.com/advisories/nltk-through-3.10.3-path-traversal-via-model-artifact-apis Third Party Advisory
https://github.com/nltk/nltk/security/advisories/GHSA-8mgp-746c-j5xp ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2026-0848Nltk improper input validation vulnerabilityNLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to improper input validation in the StanfordSegmenter module. The module dynamic…EPSS 0.81%9.4CVE-2026-78683Nltk deserialization of untrusted data vulnerabilityNLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the TransitionParser.parse() method (nltk/p…EPSS 0.51%9.3CVE-2026-79675Nltk argument injection vulnerabilityNLTK before 3.10.3 fails to validate JVM options passed through the per-call options parameter in the java() function, allowing attackers to inject d…EPSS 0.78%9.3CVE-2026-79657Nltk deserialization of untrusted data vulnerabilityNLTK versions before 3.10.3 contain a remote code execution vulnerability in allowlisted pickle loaders that trust entire module namespaces instead o…EPSS 1.3%8.8CVE-2026-79674Nltk vulnerabilityNLTK versions before 3.10.3 contain a path sandbox bypass vulnerability in corpus-reader constructors that allows attackers to read files outside the…EPSS 0.39%8.8CVE-2025-14009Nltk code injection vulnerabilityA critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py…EPSS 0.95%8.7CVE-2026-81722Nltk vulnerabilitynltk PorterStemmer in versions <= 3.10.2 (fixed in 3.10.3) contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem(). …EPSS 0.52%8.7CVE-2026-80205Nltk inefficient regular expression (redos) vulnerabilityNLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that a…EPSS 0.65%

Source: NIST National Vulnerability Database (record CVE-2026-81726), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.