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Vulnerability record · CVE-2025-14009 · published 18 February 2026

CVE-2025-14009: Nltk code injection vulnerability

Nltk · Nltk

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as __init__.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

8.8 CVSS 3.1 High EPSS 0.95% · top 40.4% CWE-94 · Code injection
8.8CVSS 3.1 base score
0.95%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 2 tagged exploit
15 Jul 2026Last modified by NVD

Description

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as __init__.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

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

References

LinkTags
https://huntr.com/bounties/49ecbc02-054e-4470-b2e0-b267936cc4e4 ExploitThird Party Advisory
https://access.redhat.com/errata/RHSA-2026:10184
https://access.redhat.com/security/cve/CVE-2025-14009
https://bugzilla.redhat.com/show_bug.cgi?id=2440724
https://huntr.com/bounties/49ecbc02-054e-4470-b2e0-b267936cc4e4 ExploitThird Party Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-14009.json

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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%8.7CVE-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%8.7CVE-2026-78681Nltk vulnerabilityNLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers …EPSS 0.52%

Source: NIST National Vulnerability Database (record CVE-2025-14009), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.