CVE-2026-46338 PyMdown Extensions: Regression in pymdownx.snippets reintroduces sibling-prefix path traversal bypass despite restrict_base_path

PyMdown Extensions is a set of extensions for the Python-Markdown markdown project. From 10.0.1 until 10.21.3, pymdownx.snippets uses a string-prefix containment check in SnippetPreprocessor.getsnippetpath in pymdownx/snippets.py when restrictbasepath: True, allowing markdown snippet directives t...