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Advisory record · GHSA-r6gq-whwq-mvg9

NLTK: Symlink escape in CorpusReader allows arbitrary local file read outside the corpus root

CVSS 8.6 HighEPSS 0.0020 · 9th percentile

Published by the GitHub Advisory Database at 8 Sept 2026, 15:26 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
nltkPyPI<3.9.43.9.4
Identifiers
GHSA-r6gq-whwq-mvg9 · CVE-2026-70626 · PYSEC-2026-3732
Weakness (CWE)
CWE-59
Tags
Published
8 Sept 2026
Updated
8 Sept 2026

Machine-written summary

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

NLTK versions before 3.9.4 are affected: CorpusReader.open() checks file paths lexically and does not account for symlinks, so a symlink placed inside the corpus root can point to a file outside it. An attacker who can place or influence files inside the allowed corpus root can read arbitrary local files readable by the application user. Upgrade to NLTK 3.9.4 or later.

Written 5 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
8.6 High 4.0 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0020, the 9th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:38 UTC First seen by agentprime
  2. 31 Oct 2026, 14:38 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.