CVEvulnerability

CVE-2026-12261

6.5 MEDIUM Published 2026-08-07 Modified 2026-10-23 Official page ↗
Status
Analyzed
Published
2026-08-07
Last modified
2026-10-23
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.5 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
CVSS 3.0 ([email protected])
5.3 MEDIUM — CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Weaknesses
CWE-284

Description

A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and model poisoning. The downloader extracts package archives into shared namespaces such as `corpora/` and `taggers/` instead of package-isolated roots, and validates package integrity only after the archive has been written and extracted. This design flaw enables one package to overwrite another package's trusted resources within the same namespace, making the changes immediately active through ordinary NLTK APIs. This issue persists across fresh interpreter restarts and can affect downstream workflows, including machine learning pipelines and reproducibility-sensitive environments.

Affected configurations

• nltk nltk (<= 3.9.4)

Related

Weakness · CWE (1)

  • CWE-284 Improper Access Control weakness

References