PyPI/nltk CVE-2026-81727: high 7.1, EPSS 0.19%

NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite files outside the i

Action: Upgrade nltk to 3.10.3 or later.

pip install nltk==3.10.3

Affected

Fixed versions

Sources

• osv: PYSEC-2026-3741
• nvd: CVE-2026-81727
• https://www.vulncheck.com/advisories/nltk-before-3.10.3-hardlink-file-overwrite-via-downloader
• https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672

CVE-2026-81727 · published 2026-08-27T17:21:03.533Z · modified 2026-09-01T09:15:03.611585308Z · JSON