---
id: CVE-2026-71514
title: >-
  NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in
  CrubadanCorpusReader
summary: >-
  NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in
  CrubadanCorpusReader. _load_lang_ngrams joins the corpus root with
  crubadan_code, the column-0 value read from the corpus table.txt mapping file,
  and opens the result w…
severity: low
cvss: 2.5
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N'
cwe:
  - CWE-22
published: '2026-08-22'
updated: '2026-08-22'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-71514'
references:
  - url: 'https://github.com/nltk/nltk'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/nltk/nltk/blob/v3.10.2/nltk/corpus/reader/crubadan.py#L90-L98
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/nltk/nltk/commit/10d34b3f4fe3fec74b76527a409eb0acbac2e8ab
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nltk-through-path-traversal-via-crubadancorpusreader-pathsec-bypass
    label: disclosure@vulncheck.com
  - url: 'https://github.com/advisories/GHSA-cv22-g7mw-8v73'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-71514'
  - url: 'https://github.com/nltk/nltk/releases/tag/v3.10.3'
tags:
  - nvd
  - osv
  - pip
ingestedAt: '2026-08-23T04:42:15.010Z'
epss: 0.00171
epssPercentile: 0.05779
aliases:
  - PYSEC-2026-3790
  - GHSA-cv22-g7mw-8v73
ecosystem: pip
vendor: nltk
product: nltk
affected:
  - 'nltk >= 3.9.4, < 3.10.3'
patched:
  - nltk 3.10.3
scores:
  nvd: 2.5
  osv: 3.3
---

## Overview

NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in CrubadanCorpusReader. _load_lang_ngrams joins the corpus root with crubadan_code, the column-0 value read from the corpus table.txt mapping file, and opens the result with the builtin open() rather than the pathsec-validated opener, so os.path.join discards the root when that value is absolute and the read escapes the corpus directory without the containment check nltk.pathsec applies when ENFORCE is set. An attacker who controls a corpus package can disclose file contents outside the corpus root through lang_freq, limited to paths ending in -3grams.txt whose contents parse as token count lines.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-71514)

Affected packages:

- `nltk >= 3.9.4, < 3.10.3`

Patched in:

- `nltk 3.10.3`

Source: https://osv.dev/vulnerability/PYSEC-2026-3790