CVE-2026-33236
Path Traversal in NLTK Downloader Allows Arbitrary File Overwrite
Publication date: 2026-03-20
Last updated on: 2026-03-23
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| nltk | nltk | to 3.9.3 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-22 | The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the NLTK (Natural Language Toolkit) downloader in versions 3.9.3 and prior. The downloader does not properly validate the 'subdir' and 'id' attributes when processing remote XML index files. An attacker who controls a remote XML index server can supply malicious values containing path traversal sequences like '../'. This can lead to arbitrary directory creation, file creation, and file overwrite on the system where the downloader runs.
How can this vulnerability impact me? :
The vulnerability can allow an attacker to create or overwrite files and directories arbitrarily on the affected system. This can lead to potential disruption of service, unauthorized modification of files, or execution of malicious code. The CVSS score of 8.1 indicates a high severity with impacts on integrity and availability.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, update NLTK to a version later than 3.9.3 where the issue is patched (commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a). This update addresses the improper validation of the `subdir` and `id` attributes in the downloader, preventing path traversal attacks.