Vulnerability in Facelessuser Pymdown-Extensions
CVE-2025-68142
PyMdown Extensions is a set of extensions for the `Python-Markdown` markdown project. Versions prior to 10.16.1 have a ReDOS bug found within the figure caption extension (`pymdownx.blocks.caption`). In systems that take unchecked user content, this could cause long hanges when processing the data if a malicious payload was crafted. This issue is patched in Release 10.16.1. As a workaround, those who process unknown user content without timeouts or other safeguards in place to prevent really large, malicious content being aimed at systems may avoid the use of `pymdownx.blocks.caption` until they're able to upgrade.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (39.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: -0.000
Affected products
- Facelessuser Pymdown-Extensions — versions < 10.16.1
- Facelessuser Pymdown Extensions
Weakness classification (CWE)
References
- github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-r6h4-mm7h-8… (Exploit, Patch, Vendor Advisory)
- github.com/facelessuser/pymdown-extensions/commit/b50d15a56850ed1408a284bba81cc… (Patch)
- pypi.org/project/pymdown-extensions/10.16.1 (Product, Release Notes)
Frequently asked questions
- What is CVE-2025-68142?
- CVE-2025-68142 is a medium-severity vulnerability in Facelessuser Pymdown-Extensions, classified under Inefficient Regular Expression Complexity. CVSS score: 5.3/10. Published 2025-12-16.
- How severe is CVE-2025-68142?
- Medium severity. CVSS v3 base score is 5.3 out of 10.