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8.8

CVE-2025-14009: NLTK allows malicious zip files to execute code

GHSA-7p94-766c-hgjp CVE-2025-14009 CVE-2025-14009
Summary

The NLTK software can extract malicious zip files, which can then run code on your system. This can lead to access to your files and network, and potentially allow an attacker to keep access even after you've removed NLTK. You should update NLTK to the latest version to fix this issue.

What to do
  • Update nltk to version 3.9.3.
Affected software
Ecosystem VendorProductAffected versions
pip – nltk <= 3.9.2
Fix: upgrade to 3.9.3
– nltk nltk < 3.9.3
cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
– nltk nltk/nltk <= latest
Original title
Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution
Original 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.
ghsa CVSS3.1 10.0
Vulnerability type
CWE-94 Code Injection
Published: 18 Feb 2026 · Updated: 31 Jul 2026 · First seen: 6 Mar 2026