CVE-2026-12261Improper Access Control in nltk/nltk
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.3 MEDIUM (v3.0, CNA)CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
- Weakness (CWE)
- CWE-284
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- @huntr_ai
- NVD analysis
- Analyzed
- Record last updated
- Aug 7, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
nltk nltk/nltk nltk:nltk (from the name) | from unspecified through latest | CNA record |
nltk nltk nltk:nltk | through 3.9.4 | NVD |
References
- https://huntr.com/bounties/8b8c381e-08a8-4e4f-bb46-a320c96a364fpermissions-required
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.