Critical Security Update for python-markdown: Denial of Service Vulnerability
Summary
ALSA-2026:19155: Important: python-markdown security update. Affects python3-markdown versions < 3.5.1-6.el10_2.1. Fixed in 3.5.1-6.el10_2.1. How to fix ↓
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Background
Python-markdown is a widely used library for converting Markdown text to HTML. It is an interpreted, interactive, object-oriented programming language that supports dynamic data types and typing. The library is essential for applications that require text formatting and web content generation. However, it has been found to be vulnerable to a denial of service attack when processing malformed HTML-like sequences.
Vulnerability Detail
The vulnerability identified as CVE-2025-69534 allows an attacker to exploit python-markdown by sending specially crafted input that can lead to a denial of service. This occurs when the library encounters malformed HTML-like sequences, causing it to hang or crash. The ramifications of this vulnerability can be significant, especially for web applications relying on markdown processing, as it could lead to service interruptions and degraded user experience.
How To Fix
Minimum fixed version
3.5.1-6.el10_2.1
This is the first release that contains the fix.
sudo dnf update python3-markdownTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate updating is not feasible, consider implementing input validation to filter out potentially malicious markdown content. This can help mitigate the risk of denial of service attacks until the package is updated.
Conclusion
The python-markdown library has a critical vulnerability that can lead to denial of service attacks. It is essential to update to the latest patched version to safeguard your applications. Implementing input validation can serve as a temporary workaround until the update is applied.
See every vulnerability recorded for python3-markdown →
FAQ
The vulnerability allows for denial of service attacks through malformed HTML-like sequences, which can cause the library to hang or crash.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The potential impacts include service interruptions and degraded user experience for applications relying on markdown processing.
Yes, a patch is available in version 3.5.1-6.el10_2.1 of the python3-markdown package.
Implement input validation to filter out potentially malicious markdown content as a temporary measure until you can update the package.
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