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.
History

Tue, 25 Aug 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-08-25T11:33:22.645Z

Updated: 2026-08-25T15:58:38.403Z

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

Link: CVE-2026-79657

cve-icon Vulnrichment

Updated: 2026-08-25T15:57:08.062Z

cve-icon NVD

Status : Analyzed

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

Modified: 2026-08-31T19:05:50.737

Link: CVE-2026-79657

cve-icon Redhat

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