Summary
Jte HTML templates with script tags or script attributes that include a Javascript template string (backticks) are subject to XSS.
Details
The javaScriptBlock and javaScriptAttribute methods in the Escape class (source) do not escape backticks, which are used for Javascript template strings. Dollar signs in template strings should also be escaped as well to prevent undesired interpolation.
PoC
- Use the Jte Gradle Plugin with the following code in
src/jte/xss.jte:
@param String someMessage
<!DOCTYPE html>
<html lang="en">
<head>
<title>XSS Test</title>
<script>window.someVariable = `${someMessage}`;</script>
</head>
<body>
<h1>XSS Test</h1>
</body>
</html>
- Use the following Java code to demonstrate the XSS vulnerability:
final StringOutput output = new StringOutput();
JtexssGenerated.render(new OwaspHtmlTemplateOutput(output), null, "` + alert(`xss`) + `");
renderHtml(output);
Impact
HTML templates rendered by Jte's OwaspHtmlTemplateOutput in versions less than or equal to 3.1.15 with script tags or script attributes that contain Javascript template strings (backticks) are vulnerable.
Summary
Jte HTML templates with
scripttags or script attributes that include a Javascript template string (backticks) are subject to XSS.Details
The
javaScriptBlockandjavaScriptAttributemethods in theEscapeclass (source) do not escape backticks, which are used for Javascript template strings. Dollar signs in template strings should also be escaped as well to prevent undesired interpolation.PoC
src/jte/xss.jte:Impact
HTML templates rendered by Jte's
OwaspHtmlTemplateOutputin versions less than or equal to3.1.15withscripttags or script attributes that contain Javascript template strings (backticks) are vulnerable.