CVE-2026-33236

Affected versions of the nltk package are vulnerable to Arbitrary File Overwrite due to improper validation of path components from remote XML index files. The vulnerability exists in nltk/downloader.py because Package.fromxml() builds self.filename with untrusted subdir and id values, _download_package() joins that filename with download_dir, calls os.makedirs() on the attacker-controlled info.subdir, and then writes the downloaded file with open(filepath, "wb") without blocking dot-dot-slash path traversal sequences.