---
id: CVE-2026-65915
title: >-
  NLTK versions before 3.10.0 contain a logic bug in
  FileSystemPathPointer.open() where the sandbox validation check compares a
  normalized path against itself, making the security check permanently inert
summary: >-
  NLTK versions before 3.10.0 contain a logic bug in
  FileSystemPathPointer.open() where the sandbox validation check compares a
  normalized path against itself, making the security check permanently inert.
  Attackers can pass file:// URLs to…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-284
published: '2026-08-22'
updated: '2026-08-22'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-65915'
references:
  - url: 'https://github.com/nltk/nltk/security/advisories/GHSA-72r2-7mfr-5xr9'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nltk-before-arbitrary-file-read-via-filesystempathpointer
    label: disclosure@vulncheck.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-65915'
  - url: 'https://github.com/nltk/nltk/pull/3522'
  - url: >-
      https://github.com/nltk/nltk/commit/69db9911fdba914ceeaca7aec6e892d1b14586a9
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3731.yaml
  - url: 'https://huntr.com/bounties/a510de7b-ffaf-4a83-9bf8-fa7e63f4bd2d'
  - url: 'https://github.com/advisories/GHSA-72r2-7mfr-5xr9'
  - url: 'https://github.com/nltk/nltk'
tags:
  - nvd
  - ghsa
  - pip
  - osv
ingestedAt: '2026-08-23T04:42:15.391Z'
epss: 0.0041
epssPercentile: 0.32644
aliases:
  - GHSA-72r2-7mfr-5xr9
  - PYSEC-2026-3731
ecosystem: pip
vendor: nltk
product: nltk
affected:
  - nltk <= 3.9.3
patched:
  - nltk 3.10.0
---

## Overview

NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, making the security check permanently inert. Attackers can pass file:// URLs to nltk.data.load() to read arbitrary files accessible to the process user, including credentials and configuration files.

## Remediation

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

## Package advisory (CVE-2026-65915)

Affected packages:

- `nltk <= 3.9.3`

Patched in:

- `nltk 3.10.0`

Source: https://github.com/advisories/GHSA-72r2-7mfr-5xr9