GHSA-J8R4-32C5-33RC xhtml-purifier has HTML attribute-injection (sanitizer bypass) that leads to XSS

xhtml-purifier does not HTML-entity-encode attribute values when serializing its sanitized output. In attributeString XHTMLPurifier.js, around line 148 the attribute value is concatenated directly into a double-quoted attribute without encoding. As a result, an attacker-controlled value in any...