CVE-2025-69534

7.5 HIGH
Published: March 05, 2026 Modified: March 13, 2026
View on NVD

Description

Python-Markdown version 3.8 contain a vulnerability where malformed HTML-like sequences can cause html.parser.HTMLParser to raise an unhandled AssertionError during Markdown parsing. Because Python-Markdown does not catch this exception, any application that processes attacker-controlled Markdown may crash. This enables remote, unauthenticated Denial of Service in web applications, documentation systems, CI/CD pipelines, and any service that renders untrusted Markdown. The issue was acknowledged by the vendor and fixed in version 3.8.1. This issue causes a remote Denial of Service in any application parsing untrusted Markdown, and can lead to Information Disclosure through uncaught exceptions.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/Python-Markdown/markdown
Source: cve@mitre.org
Product
https://github.com/Python-Markdown/markdown/issues/1534
Source: cve@mitre.org
Exploit Issue Tracking
http://www.openwall.com/lists/oss-security/2026/03/06/4
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
7.5 / 10.0
EPSS (Exploit Probability)
0.2%
48th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

python-markdown