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Vulnerability · Published Mar 20, 2026 · Assigned by GitHub_M

CVE-2026-33236NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite

High 8.1

In plain English

A high-severity path traversal in nltk from nltk. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.1High
Exploit odds (30 days)0.6%top 50.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nltkno fix listedDEBIAN-CVE-2026-33236
Debian:13nltkno fix listedDEBIAN-CVE-2026-33236
Debian:14nltk3.10.0-1DEBIAN-CVE-2026-33236
PyPInltk3.9.4PYSEC-2026-2237
PyPInltk3.9.4GHSA-469j-vmhf-r6v7
Ubuntu:25.10nltkno fix listedUBUNTU-CVE-2026-33236
Ubuntu:26.10nltkno fix listedUBUNTU-CVE-2026-33236

Affected products (as reported)

VendorProductVersions
nltk nltk <= 3.9.3

Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

References