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CVE-2025-69534

Python-Markdown has an Uncaught Exception

Impact

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.

Affected packages

EcosystemPackageAffectedFixed in
pipMarkdown< 3.8.13.8.1

Affected products

VendorProductAffected versions
Python-MarkdownMarkdown
Version 3.8

Weakness classification

CWE-400CWE-617CWE-248

References