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// String s may be user controllable
// \uFE64 is normalized to &lt;< and \uFE64 is normalized to &gt;> using KFKC
String s = &quot;"\uFE64&quot;" + &quot;script&quot;"script" + &quot;"\uFE65&quot;"; 

//validate
Pattern pattern = Pattern.compile(&quot;[&lt;&gt;]&quot;"[<>]"); // check for angle brackets
Matcher matcher = pattern.matcher(s);
if(matcher.find()) {
  System.out.println(&quot;"found black listed tag&quot;");
} else {
  // ... 
}

// normalize
s = Normalizer.normalize(s, Form.NFKC); 

String s = ""\uFE64"" + "script""script" + ""\uFE65"";

// normalize
s = Normalizer.normalize(s, Form.NFKC); 

//validate
Pattern pattern = Pattern.compile(&quot;[&lt;&gt;]&quot;"[<>]"); 
Matcher matcher = pattern.matcher(s);
if(matcher.find()) {
  System.out.println(&quot;"found black listed tag&quot;"); 
  throw new IllegalStateException();
} else {
  // ... 
}