CVE-2025-69534

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.
Configurations

Configuration 1 (hide)

cpe:2.3:a:python-markdown:markdown:3.8:*:*:*:*:python:*:*

History

30 Jun 2026, 03:16

Type Values Removed Values Added
References
  • () https://access.redhat.com/errata/RHSA-2026:10184 -
  • () https://access.redhat.com/errata/RHSA-2026:13508 -
  • () https://access.redhat.com/errata/RHSA-2026:13512 -
  • () https://access.redhat.com/errata/RHSA-2026:13826 -
  • () https://access.redhat.com/errata/RHSA-2026:14835 -
  • () https://access.redhat.com/errata/RHSA-2026:14873 -
  • () https://access.redhat.com/errata/RHSA-2026:14874 -
  • () https://access.redhat.com/errata/RHSA-2026:19155 -
  • () https://access.redhat.com/errata/RHSA-2026:19366 -
  • () https://access.redhat.com/errata/RHSA-2026:20674 -
  • () https://access.redhat.com/errata/RHSA-2026:20676 -
  • () https://access.redhat.com/errata/RHSA-2026:20677 -
  • () https://access.redhat.com/errata/RHSA-2026:9742 -
  • () https://access.redhat.com/security/cve/CVE-2025-69534 -
  • () https://bugzilla.redhat.com/show_bug.cgi?id=2444839 -
  • () https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-69534.json -
CWE CWE-617

13 Mar 2026, 01:25

Type Values Removed Values Added
First Time Python-markdown markdown
Python-markdown
CPE cpe:2.3:a:python-markdown:markdown:3.8:*:*:*:*:python:*:*
References () https://github.com/Python-Markdown/markdown - () https://github.com/Python-Markdown/markdown - Product
References () https://github.com/Python-Markdown/markdown/actions/runs/15736122892 - () https://github.com/Python-Markdown/markdown/actions/runs/15736122892 - Product
References () https://github.com/Python-Markdown/markdown/issues/1534 - () https://github.com/Python-Markdown/markdown/issues/1534 - Exploit, Issue Tracking
References () http://www.openwall.com/lists/oss-security/2026/03/06/4 - () http://www.openwall.com/lists/oss-security/2026/03/06/4 - Mailing List, Third Party Advisory

12 Mar 2026, 17:16

Type Values Removed Values Added
Summary
  • (es) Python-Markdown versión 3.8 contiene una vulnerabilidad donde secuencias malformadas similares a HTML pueden hacer que html.parser.HTMLParser genere un AssertionError no manejado durante el análisis de Markdown. Debido a que Python-Markdown no captura esta excepción, cualquier aplicación que procese Markdown controlado por el atacante puede fallar. Esto permite una denegación de servicio remota y no autenticada en aplicaciones web, sistemas de documentación, pipelines de CI/CD y cualquier servicio que renderice Markdown no confiable. El problema fue reconocido por el proveedor y corregido en la versión 3.8.1. Este problema causa una denegación de servicio remota en cualquier aplicación que analice Markdown no confiable, y puede llevar a la revelación de información a través de excepciones no capturadas.
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 7.5
CWE CWE-400

06 Mar 2026, 21:16

Type Values Removed Values Added
References
  • () http://www.openwall.com/lists/oss-security/2026/03/06/4 -

05 Mar 2026, 15:16

Type Values Removed Values Added
New CVE

Information

Published : 2026-03-05 15:16

Updated : 2026-07-15 02:17


NVD link : CVE-2025-69534

Mitre link : CVE-2025-69534

CVE.ORG link : CVE-2025-69534


JSON object : View

Products Affected

python-markdown

  • markdown
CWE
CWE-400

Uncontrolled Resource Consumption

CWE-617

Reachable Assertion