medium6.1
CVE-2026-44897
Mistune is a Python Markdown parser with renderers and plugins.
Impact
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading() builds the opening <hN> tag by string-concatenating the id attribute value directly into the HTML — with no call to escape(), safe_entity(), or any other sanitisation function. A double-quote character " in the id value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, src=, href=, etc.) into the heading element. This vulnerability is fixed in 3.2.1.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | mistune | <= 3.2.0 | 3.2.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mistune Project | Mistune | before 3.2.1 |