Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in dashbitco lazyhtml allows mutation XSS via a parse and serialize round-trip of attacker-supplied HTML.

LazyHTML.tohtml/2 and LazyHTML.Tree.tohtml/2 decide whether to escape an element's text from its tag name alone. A style or script element inside SVG or MathML foreign content is parsed with character references decoded, but is serialized as an HTML raw-text element, so its text is emitted unescaped. Encoded markup such as &lt;/style&gt;&lt;img src=x onerror=...&gt; inside <svg><style> therefore closes the element on re-parse and becomes live markup. Applications that parse untrusted HTML with lazyhtml, filter the document or tree, and serialize it for display are affected, since the payload is a plain text node that no element or attribute filter sees.

This issue affects lazyhtml: from 0.1.0 before 0.1.13.