CVE-2026-61632
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk33th percentile - higher than 33% of all known CVEs
Summary
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. This issue has been fixed in version 11.0.
Risk Assessment
An application rendering untrusted Markdown with pymdownx.b64 enabled could 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.
Recommendation
Update PyMdown Extensions to version 11.0 or later to eliminate the path traversal vulnerability.
Other vulnerabilities in PyMdown Extensions
See all- CVE-2026-67422High
pymdown-extensions up to version 11.0 contains a vulnerability to catastrophic backtracking in four inline processors (caret, tilde, betterem, magiclink). A single untrusted Markdown line under 50 bytes can cause unbounded CPU usage, enabling a remote attacker to cause denial of service. The issue is fixed in version 11.0.1.
- CVE-2026-46338Medium
A vulnerability in PyMdown Extensions (versions 10.0.1 through 10.21.3) allows bypassing the base path restriction in the SnippetPreprocessor.get_snippet_path() function. The string-prefix containment check enables reading files from sibling directories sharing the same base_path prefix, representing a regression of the fix for CVE-2023-32309.
Original NVD description (English source)
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.