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CVE-2026-79657

Nltk remote code execution

9.8 CRITICALPublic exploitEPSS 1.27%
  1. Published25 Aug 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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Nltk< 3.10.3

Remediation

Fixed in
Nltk≥ 3.10.3

References

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Frequently asked

Is CVE-2026-79657 being actively exploited?

CVE-2026-79657 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 1.27%.

How severe is CVE-2026-79657?

CVE-2026-79657 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 1.27% probability of exploitation.

Which products are affected by CVE-2026-79657?

Affected products include Nltk.

How do I fix CVE-2026-79657?

Upgrade affected software to a fixed version, for example Nltk 3.10.3 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-79657 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.