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Vulnerability · Published Feb 18, 2026 · Assigned by @huntr_ai

CVE-2025-14009Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution

High 8.8

In plain English

A high-severity code injection in nltk/nltk from nltk. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 64% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High
Exploit odds (30 days)1.0%top 35.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.24py3-nltk3.9.3-r0ALPINE-CVE-2025-14009
Debian:12nltkno fix listedDEBIAN-CVE-2025-14009
Debian:13nltkno fix listedDEBIAN-CVE-2025-14009
Debian:14nltk3.9.3-1DEBIAN-CVE-2025-14009
PyPInltk3.9.3PYSEC-2026-96
PyPInltk3.9.3GHSA-7p94-766c-hgjp
Ubuntu:25.10nltkno fix listedUBUNTU-CVE-2025-14009
Ubuntu:26.10nltkno fix listedUBUNTU-CVE-2025-14009

Affected products (as reported)

VendorProductVersions
nltk nltk/nltk unspecified – through latest

Weakness: CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References