CVE-2026-44896
Mistune Markdown Parser Attribute Injection and XSS Vulnerability
Publication date: 2026-05-26
Last updated on: 2026-05-26
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| lepture | mistune | to 3.2.0 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-79 | The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in Mistune, a Python Markdown parser. In versions 3.2.0 and earlier, the render_figure() function in the image.py file concatenates the figclass and figwidth options directly into HTML attributes without escaping them. This improper handling allows an attacker to inject malicious attributes, leading to Cross-Site Scripting (XSS) attacks, even when the HTMLRenderer is set to escape HTML content.
How can this vulnerability impact me? :
The vulnerability can lead to attribute injection and Cross-Site Scripting (XSS) attacks. This means that an attacker could inject malicious scripts into web pages rendered by Mistune, potentially compromising the security of users by executing unauthorized scripts in their browsers. This can result in data theft, session hijacking, or other malicious activities.