CVE-2026-79657

Critical

Description

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.

SeverityCritical

CVSS9.8

Exploit probability—

ProductNltk

PublishedAug 25, 2026

First seenAug 25, 2026

Weakness typeCWE-502Deserialization of untrusted data

How to fix

Update

nltk nltk3.10.3 or later
nltk3.10.3 or later

Vendor advisories

github.com/nltk/nltk/security/advisories/GHSA-x99w-6fgc-pmfw

Affected products

Product	Affected versions	Fixed in
nltk nltk	v < 3.10.3	3.10.3
nltkPyPI	v < 3.10.3	3.10.3

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.