# CVE-2025-14009: python3-nltk: A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions

CVE-2025-14009 is fixed in 3 products on 1 platform, first by python-nltk 3.2.5-1ubuntu0.1+esm3, released February 18, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-14009
- Priority: High
- CVSS: 8.8 (High)
- EPSS: 0.0104
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 18, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | nltk Debian 14 | 3.9.3-1 | [DEBIAN-CVE-2025-14009](https://patchblox.com/security/data/fix/linux/debian-cve-2025-14009.md) | Feb 18, 2026 |
| Linux | python-nltk Ubuntu 18.04.6 LTS (bionic) | 3.2.5-1ubuntu0.1+esm3 | [python-nltk 3.2.5-1ubuntu0.1+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-nltk-3.2.5-1ubuntu0.1-esm3.md) | Feb 18, 2026 |
| Linux | python3-nltk Ubuntu 18.04.6 LTS (bionic) | 3.2.5-1ubuntu0.1+esm3 | [python3-nltk 3.2.5-1ubuntu0.1+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-nltk-3.2.5-1ubuntu0.1-esm3.md) | Feb 18, 2026 |
| Linux | python3-nltk Ubuntu 20.04 LTS (focal) | 3.4.5-2ubuntu0.1~esm3 | [python3-nltk 3.4.5-2ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-nltk-3.4.5-2ubuntu0.1-esm3.md) | Feb 18, 2026 |
| Linux | python3-nltk Ubuntu 22.04.1 LTS (jammy) | 3.7-1ubuntu0.1~esm1 | [python3-nltk 3.7-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-python3-nltk-3.7-1ubuntu0.1-esm1.md) | Feb 18, 2026 |
| Linux | python3-nltk Ubuntu 24.04.5 LTS (noble) | 3.8.1-1ubuntu0.1~esm1 | [python3-nltk 3.8.1-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-python3-nltk-3.8.1-1ubuntu0.1-esm1.md) | Feb 18, 2026 |
| Linux | python3-nltk Ubuntu 26.04.1 LTS (resolute) | 3.9.2-1ubuntu0.1~esm1 | [python3-nltk 3.9.2-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-nltk-3.9.2-1ubuntu0.1-esm1.md) | Feb 18, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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