NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on… (CVE-2026-81726)

NLTK up to version 3.10.3 has a path traversal vulnerability in its model-artifact APIs. The vulnerability arises because these APIs use raw file operations on paths controlled by the caller, bypassing path security (pathsec) enforcement. This allows an attacker to access or modify files outside the allowed sandbox roots via the TransitionParser, AveragedPerceptron, PerceptronTagger, and maxent parameter APIs when pathsec is enabled. The CVSS 3.1 score is 7.0, indicating a medium severity with network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, high confidentiality impact, low integrity impact, and low availability impact.

An attacker can exploit this vulnerability to read or write files outside the intended sandbox, potentially exposing sensitive information or modifying files on the system. The impact includes high confidentiality loss, low integrity, and availability impacts. No privileges or user interaction are required, but the attack complexity is high.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, users should monitor vendor communications for updates. Until a fix is available, avoid enabling pathsec or using the affected model-artifact APIs with untrusted input paths.