CVE-2026-79657

NLTK versions before 3.10.3 contain a remote code execution vulnerability in allowlisted pickle loaders that trust entire module namespaces instead of specific safe callables. Attackers can craft malicious pickle payloads invoking dangerous in-namespace functions like ReppTokenizer._execute and numpy.f2py.crackfortran.myeval through pickle REDUCE to execute arbitrary commands during model or tokenizer artifact loading.

Affected products

Nltk

CVSS 3.1

9.8 CRITICAL

EPSS

1.2% (65th percentile)

Weakness

CWE-502

NVD status

Received

Published

2026-08-25