CVE-2026-61632 PyMdown Extensions: Path traversal in the b64 extension lets <img src> read files outside base_path

PyMdown Extensions is a set of extensions for the Python-Markdown markdown project. In versions up to and including 10.21.3, the b64 extension is vulnerable to a path traversal that discloses arbitrary files: it inlines images referenced by by joining the src onto the configured basepath with...

PYSEC-2026-3609 PyMdown Extensions: Path traversal in the b64 extension lets <img src> read files outside base_path

Summary The b64 extension inlines images referenced by as base64 data URIs. When resolving the src path it joins it onto the configured basepath with os.path.normpath and opens the result directly, with no check that the resolved path stays inside basepath. A src containing ../ sequences, or an...