Vulnerability · Published Dec 16, 2025 · Assigned by GitHub_M
CVE-2025-68142PyMdown Extensions has ReDOS bug in Figure Capture extension
Low 2.7
In plain English
A low-severity regular-expression denial of service in pymdown-extensions from facelessuser. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% 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. 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | pymdown-extensions | 10.13-1+deb13u1 | DEBIAN-CVE-2025-68142 |
| Debian:14 | pymdown-extensions | 10.13-4 | DEBIAN-CVE-2025-68142 |
| PyPI | pymdown-extensions | 10.16.1 | GHSA-r6h4-mm7h-8pmq |
| PyPI | pymdown-extensions | 10.16.1 | PYSEC-2026-1825 |
| Ubuntu:24.04:LTS | pymdown-extensions | no fix listed | UBUNTU-CVE-2025-68142 |
| Ubuntu:25.10 | pymdown-extensions | no fix listed | UBUNTU-CVE-2025-68142 |
| Ubuntu:26.04:LTS | pymdown-extensions | no fix listed | UBUNTU-CVE-2025-68142 |
| Ubuntu:26.10 | pymdown-extensions | no fix listed | UBUNTU-CVE-2025-68142 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| facelessuser | pymdown-extensions | < 10.16.1 |
Weakness: CWE-1333 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U