NLTK: Downloader.download follows hardlinks and overwrites outside-root files — GHSA-F794-5JV7-7672

Summary

### Summary NLTK's downloader now blocks symlink escapes during ZIP extraction, but it still treats pre-existing hardlinks inside the install tree as ordinary in-root files. A normal package install can therefore overwrite an outside-root inode through that hardlink. ### Details - **Vulnerability type:** Filesystem containment bypass - **Affected component:** `nltk.downloader.Downloader.download`,…

Timeline

Published by source

2026-09-02

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 6.9 out of 10.
• Reported EPSS value: 0.00135.
• Review exposure for the affected product or family: pip: nltk.

Product

pip: nltk

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-F794-5JV7-7672

Source

GitHub

Vendor

GitHub

Published by source

2026-09-02

Last source activity

2026-09-02

Additional identifiers

CVE-2026-81727

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.