Pypi · Mistune · CVE-2026-44899
**Name of the Vulnerable Software and Affected Versions**
mistune (affected versions not specified)
**Description**
The Image directive plugin fails to properly validate the `:width:` and `:height:` options. The validation uses a regular expression that only checks if the value starts with a digit, rather than ensuring the entire string is a valid number. When a value is not a plain integer, it is inserted directly into a `style` attribute without escaping.
This allows an attacker to inject arbitrary CSS properties by providing a value that begins with digits followed by malicious CSS. For example, using the `:width:` parameter, an attacker can inject properties such as `position:fixed`, `background-color`, and `z-index` to create a full-page phishing overlay or perform UI redressing attacks, effectively covering the entire browser viewport and concealing legitimate page content.
**Recommendations**
At the moment, there is no information about a newer version that contains a fix for this vulnerability.