CVE-2026-33236: Nltk

High severity, CVSS 8.1. EPSS: 0.7% chance of exploitation in the next 30 days.

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.

Affected products

• Nltk Nltk: up to and including 3.9.3

Published 2026-03-20. Last modified 2026-07-21.