CVE-2026-79657
NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization
- State
- Published
- Severity
- 9.3 Critical
- Published
- Aug 25, 2026
- Updated
- Oct 8, 2026
- Reserved
- Aug 25, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.3 Critical | 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 | VulnCheck |
| 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | VulnCheck |
Weaknesses
- CWE-502 Deserialization of Untrusted Data
Affected Products
| Product | Versions |
|---|---|
nltknltk |
|
References
- GitHub Security Advisory (GHSA-x99w-6fgc-pmfw)vendor-advisory
- VulnCheck Advisory: NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserializationthird-party-advisory
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