CVE-2026-79657

NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization

Published Aug 25, 2026 CVSS 4.0 · 9.3 Critical EPSS 1.5% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-x99w-6fgc-pmfw NLTK: Allowlisted pickle loaders still permit code execution in current source
History
Type Values Removed Values Added
Metrics ssvc

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

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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 8, 2026, 3:25 PM
Reserved
Aug 25, 2026, 11:09 AM
Status
Analyzed
Published
Aug 25, 2026, 12:16 PM
Modified
Oct 8, 2026, 4:17 PM