What it is
NLTK data downloads often run during bootstrap, notebooks, CI, model preparation, or worker startup. A vulnerable downloader matters wherever those paths can pull a malicious or compromised data package.
How it happens
CVE-2025-14009 is a Zip Slip in NLTK's data downloader, fixed in NLTK 3.9.3. When the downloader extracts a package archive, entries with crafted paths can be written outside the NLTK data directory, including into places Python later imports code from.
What an attacker gets
If an affected NLTK release downloads and extracts a malicious or compromised data package, files can land outside the intended directory and later run as code in your worker, notebook, or CI job, with whatever credentials that process holds.
// what fixvibe reports
What FixVibe reports
Runs when you connect a GitHub repository, on Pro and above. Each finding shows the file and line, its severity and fix steps you can paste into your AI coding tool.
How to fix it
Upgrade `nltk` to 3.9.3 or newer, regenerate the active Python lockfile, and rebuild every runtime, CI job, worker, notebook, or image that can call NLTK downloader code. Review `nltk.download()` and custom NLTK data mirror/cache usage so package sources stay trusted, then verify with dependency-tree and benign application tests.