Critical 9.8Published Aug 25, 2026

CVE-2026-79657NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization

Updated under an hour ago (2026-10-19 06:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-502
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Analyzed
Record last updated: Oct 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nltk nltk nltk:nltk (from the name)	before 3.10.3; 3.10.3 not affected	CNA record
nltk nltk nltk:nltk	before 3.10.3	NVD

References

https://github.com/nltk/nltk/security/advisories/GHSA-x99w-6fgc-pmfwvendor-advisory
https://www.vulncheck.com/advisories/nltk-before-3.10.3-remote-code-execution-via-unsafe-pickle-deserializationthird-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.