CVE-2026-126296

NLTK could read or overwrite model parameter files outside its allowed directories

NLTK project · Natural Language Toolkit maximum entropy model parameters

First documented disclosure · Review checkpoint

Summary

The maximum entropy parameter reader and writer opened paths without applying NLTK’s configured restrictions. Parameter files outside the approved data roots could be read or overwritten within process permissions.

Severity and exploitation evidence

Medium · 6.3/10 · CVSS 4.0. Severity source.

Exploitation not established: The reviewed advisory does not report malicious exploitation.

Exploitation evidence source

Technical severity is not a measure of observed attacks or of risk to your deployment. Attempts, demonstrations, and successful compromise retain the qualifications in the source.

How the weakness works

The maximum entropy parameter reader and writer opened paths without applying NLTK’s configured restrictions.

Conditions required

An untrusted party could influence the model parameter directory.

Potential impact

Parameter files outside the approved data roots could be read or overwritten within process permissions.

Affected versions and configurations

Through 3.10.3.

Fix and mitigation status

3.10.4.

Practical next steps

Upgrade NLTK to 3.10.4 or later. Constrain the directories accepted for reading or writing model parameters.

Operating lesson

Enforce the same filesystem policy when importing and exporting model parameters.

Evidence and limits

The CVE record was published on 2026-11-13.

Sources