GitHub Advisoryadvisory · PyPI

GHSA-5wmx-573v-2qwq Python-Markdown has an Uncaught Exception

MEDIUM Published 2026-03-05 Modified 2026-06-06 Official page ↗
Aliases
CVE-2025-69534
Ecosystem
PyPI
Packages
Markdown
Severity
Moderate
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-248, CWE-400
Reviewed
2026-03-05

Affected packages

• PyPI Markdown: < 3.8.1 → fixed in 3.8.1

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.

Related

Alias · CVE (1)

  • CVE-2025-69534 Python-Markdown version 3.8 contain a vulnerability where malformed HTML-like sequences can cause html.parser.HTMLParser to raise an… vulnerability

Weakness · CWE (2)

  • CWE-248 Uncaught Exception weakness
  • CWE-400 Uncontrolled Resource Consumption weakness

References