Some HTML elements, such as <title> and <textarea>, can contain literal angle brackets without treating them as markup. It is possible to pass a literal closing tag to .innerHTML on these elements, and subsequent content after that will be parsed as if it were outside the tag. This can lead to XSS if a site does not filter user input as strictly for these elements as it does for other elements. This vulnerability affects Firefox <69,Thunderbird<68.1,Thunderbird<60.9,FirefoxESR<60.9,andFirefoxESR<68.1.