Skip to content
OpenAdvisories
High · 8.1 CVE-2026-33236 EUVD-2026-13887GHSA-469j-vmhf-r6v7PYSEC-2026-2237

NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite

Published Mar 20, 2026 · Updated Jul 21, 2026 · Assigned by GitHub_M

Description

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

VendorProductAffectedFixed
nltk nltk <= 3.9.3 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 nltk 3.10.0-1 —
Debian 13 nltk No fix yet —
Debian 12 nltk No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 nltk No fix yet —
Ubuntu 25.10 nltk No fix yet —
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 26.04 LTS nltk 3.9.2-1ubuntu0.1~esm2 —
Ubuntu Pro 24.04 LTS nltk 3.8.1-1ubuntu0.1~esm2 —
Ubuntu Pro 22.04 LTS nltk 3.7-1ubuntu0.1~esm2 —
Ubuntu Pro 20.04 LTS nltk 3.4.5-2ubuntu0.1~esm4 —
Ubuntu Pro 18.04 LTS nltk 3.2.5-1ubuntu0.1+esm4 —
Ubuntu Pro 16.04 LTS nltk 3.1-1ubuntu0.1+esm4 —
Ubuntu Pro 14.04 LTS nltk 2.0~b9-0ubuntu4.1~esm6 —

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling py3-nltk +3 3.9.4-r0 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI nltk < 3.9.4 3.9.4 GHSA-469j-vmhf-r6v7

Advisories 1

References