CVE-2026-126302

A symlink could redirect NLTK Chat-80 to a database outside its data roots

NLTK project · Natural Language Toolkit Chat-80 database access

First documented disclosure · Review checkpoint

Summary

A database path passed the initial data-root check, then a symlink redirected the actual open operation. The affected component could read a SQLite database outside its intended sandbox.

Severity and exploitation evidence

Medium · 4.8/10 · 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

A database path passed the initial data-root check, then a symlink redirected the actual open operation.

Conditions required

An attacker could write into a trusted NLTK data directory used by Chat-80.

Potential impact

The affected component could read a SQLite database outside its intended sandbox.

Affected versions and configurations

3.9.4 through 3.10.3.

Fix and mitigation status

3.10.4.

Practical next steps

Upgrade NLTK to 3.10.4 or later. Restrict write access to NLTK data roots.

Operating lesson

Check the resolved filesystem object before opening a database.

Evidence and limits

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

Sources