GHSA-q5h6-fcf5-49g9

Duplicate Advisory: Arbitrary File Read via Path Traversal in nltk.data.load() through Percent-Encoded Sequences

Published

2026-06-30

Modified

2026-08-13

Sources

github-advisory

Summary

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-m42h-3232-vpv3. This link is maintained to preserve external references. ## Original Description NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The `_UNSAFE_NO_PROTOCOL_RE` regex in `nltk/data.py` checks for literal `../` sequences but fails to account for percent-encoded traversal sequences such as `..%2f`. The `url2pathname()` function decodes these sequences after the validation step, allowing an attacker to bypass the protection. This vulnerability enables an attacker to read arbitrary files accessible to the Python process by controlling the resource name parameter passed to `nltk.data.load()` or `nltk.data.find()`. The issue affects applications that rely on NLTK for resource loading, including NLP web applications, Jupyter notebooks, and CLI tools. The default `pathsec.ENFORCE=False` setting exacerbates the impact by not blocking the file read at the `open()` stage.

Affected packages

Remediation: No patched version is listed by GitHub.

References

• https://github.com/advisories/GHSA-q5h6-fcf5-49g9