CVE-2026-61632

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

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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 <img src="..."> by joining the src onto the configured base_path with os.path.normpath and opening the result directly, without verifying that the resolved path stays inside base_path. As a result, an src containing ../ sequences or an absolute path reads a file outside base_path as long as it has an allowed image extension (.png, .jpg, .jpeg, .gif, .svg), and the file's contents are then base64-encoded into the rendered output, disclosing them. An application that renders untrusted Markdown with pymdownx.b64 enabled can therefore leak the contents of image-extension files readable by the process to whoever controls the Markdown or views the output, a targeted file-read bounded by the extension check. This issue has been fixed in version 11.0.

CVSS 5.3 · Medium · EPSS 0.4% · Fix available

Published

2026-08-06T20:59:20.177Z

Updated

2026-08-07T17:09:02.752Z

Stack: system · python

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