CVE-2026-79657Public exploitNetwork attack vector

Remote code execution via namespace-trusting pickle allowlist

Published Aug 25, 2026 · Updated Aug 25, 2026

Deserialization of untrusted data in NLTK before 3.10.3 allows remote attackers to execute arbitrary commands through crafted artifacts. The affected pickle loaders trust entire module namespaces, letting REDUCE invoke ReppTokenizer._execute or numpy.f2py.crackfortran.myeval. Exploitation requires an application to load an attacker-controlled model or tokenizer artifact, and commands run with that application's privileges.

CVSS severity9.3
Critical
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization of untrusted data in NLTK before 3.10.3 allows remote attackers to execute arbitrary commands through crafted artifacts. The affected pickle loaders trust entire module namespaces, letting REDUCE invoke ReppTokenizer._execute or numpy.f2py.crackfortran.myeval. Exploitation requires an application to load an attacker-controlled model or tokenizer artifact, and commands run with that application's privileges.

The record

CVE
CVE-2026-79657
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
NLTK Project
Product
NLTK
Classifications
CWE-502, CWE-693, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.10.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NLTK Project · NLTKversion=0 <3.10.3

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
CWE-693Protection Mechanism Failure
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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