CVE-2026-33236

Publication date 20 March 2026

Last updated 27 May 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
nltk	26.04 LTS resolute	Fixed 3.9.2-1ubuntu0.1~esm2
	25.10 questing	Vulnerable
	24.04 LTS noble	Fixed 3.8.1-1ubuntu0.1~esm2
	22.04 LTS jammy	Fixed 3.7-1ubuntu0.1~esm2
	20.04 LTS focal	Fixed 3.4.5-2ubuntu0.1~esm4
	18.04 LTS bionic	Fixed 3.2.5-1ubuntu0.1+esm4
	16.04 LTS xenial	Ignored end of ESM support, was needs-triage
	14.04 LTS trusty	Fixed 2.0~b9-0ubuntu4.1~esm6

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
nltk	Upstream: 89fe2ec

Severity score breakdown

Parameter	Value
Base score	8.1 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

References

Related Ubuntu Security Notices (USN)

USN-8302-1
NLTK vulnerabilities
25 May 2026