Vulnerability · Published Aug 6, 2026 · Assigned by GitHub_M
CVE-2026-61632PyMdown Extensions: Path traversal in the b64 extension lets <img src> read files outside base_path
Medium 5.3
In plain English
A medium-severity path traversal in pymdown-extensions from facelessuser. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pymdown-extensions | no fix listed | DEBIAN-CVE-2026-61632 |
| Debian:13 | pymdown-extensions | no fix listed | DEBIAN-CVE-2026-61632 |
| Debian:14 | pymdown-extensions | 11.0.1-1 | DEBIAN-CVE-2026-61632 |
| PyPI | pymdown-extensions | 11.0.0 | GHSA-9xwg-3r6f-jcx2 |
| PyPI | pymdown-extensions | 11.0.0 | PYSEC-2026-3609 |
| Ubuntu:22.04:LTS | markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:24.04:LTS | markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:26.04:LTS | markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:26.10 | markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:22.04:LTS | python-markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:24.04:LTS | python-markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:26.04:LTS | python-markdown | no fix listed | UBUNTU-CVE-2026-61632 |
| Ubuntu:26.10 | python-markdown | no fix listed | UBUNTU-CVE-2026-61632 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| facelessuser | pymdown-extensions | < 11.0 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N