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.
History

Thu, 19 Feb 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important


Thu, 19 Feb 2026 10:30:00 +0000

Type Values Removed Values Added
First Time appeared Nltk
Nltk nltk
Vendors & Products Nltk
Nltk nltk

Wed, 18 Feb 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Wed, 18 Feb 2026 18:15:00 +0000

Type Values Removed Values Added
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.
Title Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution
Weaknesses CWE-94
References
Metrics cvssV3_0

{'score': 10, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: @huntr_ai

Published:

Updated: 2026-02-19T04:55:48.396Z

Reserved: 2025-12-04T09:27:21.716Z

Link: CVE-2025-14009

cve-icon Vulnrichment

Updated: 2026-02-18T19:10:39.781Z

cve-icon NVD

Status : Received

Published: 2026-02-18T18:24:19.410

Modified: 2026-02-18T20:18:31.207

Link: CVE-2025-14009

cve-icon Redhat

Severity : Important

Publid Date: 2026-02-18T17:45:17Z

Links: CVE-2025-14009 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-02-19T10:11:31Z