Arch Linux: Insufficient validation (CVE-2019-17022)

A security issue has been found in Firefox before 72.0, and Thunderbird before 68.4.1 where CSS sanitization does not escape HTML tags. When pasting a <style> tag from the clipboard into a rich text editor, the CSS sanitizer does not escape < and > characters. Because the resulting string is pasted directly into the text node of the element this does not result in a direct injection into the webpage; however, if a webpage subsequently copies the node's innerHTML, assigning it to another innerHTML, this would result in an XSS vulnerability. Two WYSIWYG editors were identified with this behavior, more may exist.