---
 nltk/app/chartparser_app.py    |   13 +++++++++++++
 nltk/corpus/reader/util.py     |    2 ++
 nltk/data.py                   |    2 ++
 nltk/parse/transitionparser.py |    2 ++
 nltk/tbl/demo.py               |    4 +++-
 5 files changed, 22 insertions(+), 1 deletion(-)

--- a/nltk/app/chartparser_app.py
+++ b/nltk/app/chartparser_app.py
@@ -800,6 +800,10 @@ class ChartComparer:
             showerror("Error Saving Chart", f"Unable to open file: {filename!r}\n{e}")
 
     def load_chart_dialog(self, *args):
+        showerror("Security Error",
+                  "Due to gh#nltk/nltk#3266, deserializing from " +
+                  "a pickle is forbidden.")
+        return
         filename = askopenfilename(
             filetypes=self.CHART_FILE_TYPES, defaultextension=".pickle"
         )
@@ -811,6 +815,8 @@ class ChartComparer:
             showerror("Error Loading Chart", f"Unable to open file: {filename!r}\n{e}")
 
     def load_chart(self, filename):
+        raise RuntimeError("Due to gh#nltk/nltk#3266, deserializing from " +
+                           "a pickle is forbidden.")
         with open(filename, "rb") as infile:
             chart = pickle.load(infile)
         name = os.path.basename(filename)
@@ -2268,6 +2274,10 @@ class ChartParserApp:
         if not filename:
             return
         try:
+            showerror("Security Error",
+                      "Due to gh#nltk/nltk#3266, deserializing from " +
+                      "a pickle is forbidden.")
+            return
             with open(filename, "rb") as infile:
                 chart = pickle.load(infile)
             self._chart = chart
@@ -2306,6 +2316,9 @@ class ChartParserApp:
             return
         try:
             if filename.endswith(".pickle"):
+                showerror("Due to gh#nltk/nltk#3266, deserializing from " +
+                          "a pickle is forbidden.")
+                return
                 with open(filename, "rb") as infile:
                     grammar = pickle.load(infile)
             else:
--- a/nltk/corpus/reader/util.py
+++ b/nltk/corpus/reader/util.py
@@ -521,6 +521,8 @@ class PickleCorpusView(StreamBackedCorpu
 
     def read_block(self, stream):
         result = []
+        raise RuntimeError("Due to gh#nltk/nltk#3266, deserializing from " +
+                           "a pickle is forbidden.")
         for i in range(self.BLOCK_SIZE):
             try:
                 result.append(pickle.load(stream))
--- a/nltk/data.py
+++ b/nltk/data.py
@@ -752,6 +752,8 @@ def load(
     if format == "raw":
         resource_val = opened_resource.read()
     elif format == "pickle":
+        raise RuntimeError("Due to gh#nltk/nltk#3266, deserializing from " +
+                           "a pickle is forbidden.")
         resource_val = pickle.load(opened_resource)
     elif format == "json":
         import json
--- a/nltk/parse/transitionparser.py
+++ b/nltk/parse/transitionparser.py
@@ -553,6 +553,8 @@ class TransitionParser(ParserI):
         """
         result = []
         # First load the model
+        raise RuntimeError("Due to gh#nltk/nltk#3266, deserializing from " +
+                           "a pickle is forbidden.")
         model = pickle.load(open(modelFile, "rb"))
         operation = Transition(self._algorithm)
 
--- a/nltk/tbl/demo.py
+++ b/nltk/tbl/demo.py
@@ -253,6 +253,8 @@ def postag(
                 )
             )
         with open(cache_baseline_tagger) as print_rules:
+            raise RuntimeError("Due to gh#nltk/nltk#3266, deserializing from " +
+                               "a pickle is forbidden.")
             baseline_tagger = pickle.load(print_rules)
             print(f"Reloaded pickled tagger from {cache_baseline_tagger}")
     else:
@@ -327,7 +329,7 @@ def postag(
         with open(serialize_output) as print_rules:
             brill_tagger_reloaded = pickle.load(print_rules)
         print(f"Reloaded pickled tagger from {serialize_output}")
-        taggedtest_reloaded = brill_tagger.tag_sents(testing_data)
+        taggedtest_reloaded = brill_tagger_reloaded.tag_sents(testing_data)
         if taggedtest == taggedtest_reloaded:
             print("Reloaded tagger tried on test set, results identical")
         else: