# CVE-2026-0847: nltk: A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal in multiple...

CVE-2026-0847 is fixed in 3 products on 1 platform, first by DEBIAN-CVE-2026-0847, released March 4, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-0847
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0100
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 4, 2026

## Description

A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling attackers to traverse directories and access sensitive files on the server. This issue is particularly critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs, chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to remote code execution when combined with other vulnerabilities.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | nltk Debian 14 | 3.9.3-1 | [DEBIAN-CVE-2026-0847](https://patchblox.com/security/data/fix/linux/debian-cve-2026-0847.md) | Mar 4, 2026 |
| Linux | python-nltk Ubuntu 18.04.6 LTS (bionic) | 3.2.5-1ubuntu0.1+esm4 | [python-nltk 3.2.5-1ubuntu0.1+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-nltk-3.2.5-1ubuntu0.1-esm4.md) | Mar 20, 2026 |
| Linux | python3-nltk Ubuntu 18.04.6 LTS (bionic) | 3.2.5-1ubuntu0.1+esm4 | [python3-nltk 3.2.5-1ubuntu0.1+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-nltk-3.2.5-1ubuntu0.1-esm4.md) | Mar 20, 2026 |
| Linux | python3-nltk Ubuntu 20.04 LTS (focal) | 3.4.5-2ubuntu0.1~esm4 | [python3-nltk 3.4.5-2ubuntu0.1~esm4](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-nltk-3.4.5-2ubuntu0.1-esm4.md) | Mar 20, 2026 |
| Linux | python3-nltk Ubuntu 22.04.1 LTS (jammy) | 3.7-1ubuntu0.1~esm2 | [python3-nltk 3.7-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-python3-nltk-3.7-1ubuntu0.1-esm2.md) | Mar 20, 2026 |
| Linux | python3-nltk Ubuntu 24.04.5 LTS (noble) | 3.8.1-1ubuntu0.1~esm2 | [python3-nltk 3.8.1-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-python3-nltk-3.8.1-1ubuntu0.1-esm2.md) | Mar 20, 2026 |
| Linux | python3-nltk Ubuntu 26.04.1 LTS (resolute) | 3.9.2-1ubuntu0.1~esm2 | [python3-nltk 3.9.2-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-nltk-3.9.2-1ubuntu0.1-esm2.md) | Mar 20, 2026 |

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Data as of 2026-11-08T00:53:09Z 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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