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.
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Fixes

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Workaround

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History

Tue, 25 Aug 2026 11:45:00 +0000

Type Values Removed Values Added
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.
Title NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization
First Time appeared Nltk
Nltk nltk
Weaknesses CWE-502
CPEs cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
Vendors & Products Nltk
Nltk nltk
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-25T11:36:41.768Z

Reserved: 2026-08-25T11:09:11.170Z

Link: CVE-2026-79657

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-25T12:16:28.870

Modified: 2026-08-25T12:16:28.870

Link: CVE-2026-79657

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-25T12:30:17Z

Weaknesses