CVE-2026-71513
High
Description
NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.
SeverityHigh
CVSS8.8
Exploit probability—
ProductNltk
PublishedAug 22, 2026
First seenAug 22, 2026
Weakness typeCWE-502Deserialization of untrusted data
How to fix
Update
- nltk nltk3.10.3 or later
- nltk3.10.3 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| nltk nltk | v < 3.10.3 | 3.10.3 |
| nltkPyPI | 3.10.0 ≤ v < 3.10.3 | 3.10.3 |
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