Description: Fix XSS in debugger
Origin: https://github.com/pallets/werkzeug/commit/1034edc7f901dd645ec6e462754111b39002bd65

--- a/werkzeug/debug/tbtools.py
+++ b/werkzeug/debug/tbtools.py
@@ -337,7 +337,7 @@
             'exception':        exc,
             'exception_type':   escape(self.exception_type),
             'summary':          self.render_summary(include_title=False),
-            'plaintext':        self.plaintext,
+            'plaintext':        escape(self.plaintext),
             'plaintext_cs':     re.sub('-{2,}', '-', self.plaintext),
             'traceback_id':     self.id,
             'secret':           secret