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Advisory record · GHSA-f794-5jv7-7672

NLTK: Downloader.download follows hardlinks and overwrites outside-root files

CVSS 6.9 MediumEPSS 0.0019 · 8th percentile

Published by the GitHub Advisory Database at 2 Sept 2026, 14:35 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
nltkPyPI<3.10.33.10.3
Identifiers
GHSA-f794-5jv7-7672 · CVE-2026-81727 · PYSEC-2026-3741
Weakness (CWE)
CWE-59 · CWE-61 · CWE-73
Tags
Published
2 Sept 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

NLTK versions before 3.10.3 are affected. The downloader does not reject a pre-existing hardlink inside the install tree during package extraction, so an attacker who can plant files in a writable shared downloader directory on the same filesystem can overwrite files outside the install root. The source gives few details on exact conditions beyond this. Upgrade to NLTK 3.10.3, which is the listed fixed version.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.9 Medium 4.0 CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0019, the 8th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:10 UTC First seen by agentprime
  2. 31 Oct 2026, 14:10 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.