Natural Language Toolkit (NLTK): URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read

Summary nltk.data.load in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname decodes the %xx sequences a classic decode-after-check / TOCTOU-style flaw, allowing ...

PT-2026-49738

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.0-rc1 Description The nltk.data.load function is subject to path traversal when using the nltk: URL scheme. The issue arises because the UNSAFE NO PROTOCOL RE regex check is performed on the raw resource string befo...