diff --git a/changelogs/fragments/avoid-set_options-leak.yaml b/changelogs/fragments/avoid-set_options-leak.yaml
new file mode 100644
index 00000000000..9680f444e6c
--- /dev/null
+++ b/changelogs/fragments/avoid-set_options-leak.yaml
@@ -0,0 +1,5 @@
+---
+security_fixes:
+  - Do not include params in exception when a call to ``set_options`` fails.
+    Additionally, block the exception that is returned from being displayed to stdout.
+    (CVE-2021-3620)
diff --git a/lib/ansible/cli/scripts/ansible_connection_cli_stub.py b/lib/ansible/cli/scripts/ansible_connection_cli_stub.py
index d2952bbe017..31047d96c5f 100755
--- a/lib/ansible/cli/scripts/ansible_connection_cli_stub.py
+++ b/lib/ansible/cli/scripts/ansible_connection_cli_stub.py
@@ -99,7 +99,11 @@ class ConnectionProcess(object):
                 self.play_context.private_key_file = os.path.join(self.original_path, self.play_context.private_key_file)
             self.connection = connection_loader.get(self.play_context.connection, self.play_context, '/dev/null',
                                                     task_uuid=self._task_uuid, ansible_playbook_pid=self._ansible_playbook_pid)
-            self.connection.set_options(var_options=variables)
+            try:
+                self.connection.set_options(var_options=variables)
+            except ConnectionError as exc:
+                messages.append(('debug', to_text(exc)))
+                raise ConnectionError('Unable to decode JSON from response set_options. See the debug log for more information.')
 
             self.connection._socket_path = self.socket_path
             self.srv.register(self.connection)
@@ -301,7 +305,11 @@ def main():
             else:
                 messages.append(('vvvv', 'found existing local domain socket, using it!'))
                 conn = Connection(socket_path)
-                conn.set_options(var_options=variables)
+                try:
+                    conn.set_options(var_options=variables)
+                except ConnectionError as exc:
+                    messages.append(('debug', to_text(exc)))
+                    raise ConnectionError('Unable to decode JSON from response set_options. See the debug log for more information.')
                 pc_data = to_text(init_data)
                 try:
                     conn.update_play_context(pc_data)
diff --git a/lib/ansible/module_utils/connection.py b/lib/ansible/module_utils/connection.py
index a76fdb6bcc3..fd0b134087c 100644
--- a/lib/ansible/module_utils/connection.py
+++ b/lib/ansible/module_utils/connection.py
@@ -163,6 +163,11 @@ class Connection(object):
         try:
             response = json.loads(out)
         except ValueError:
+            # set_option(s) has sensitive info, and the details are unlikely to matter anyway
+            if name.startswith("set_option"):
+                raise ConnectionError(
+                    "Unable to decode JSON from response to {0}. Received '{1}'.".format(name, out)
+                )
             params = [repr(arg) for arg in args] + ['{0}={1!r}'.format(k, v) for k, v in iteritems(kwargs)]
             params = ', '.join(params)
             raise ConnectionError(
diff --git a/test/units/module_utils/test_connection.py b/test/units/module_utils/test_connection.py
new file mode 100644
index 00000000000..bd0285b3a72
--- /dev/null
+++ b/test/units/module_utils/test_connection.py
@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+# Copyright: (c) 2021, Matt Martz <matt@sivel.net>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+from ansible.module_utils import connection
+
+import pytest
+
+
+def test_set_options_credential_exposure():
+    def send(data):
+        return '{'
+
+    c = connection.Connection(connection.__file__)
+    c.send = send
+    with pytest.raises(connection.ConnectionError) as excinfo:
+        c._exec_jsonrpc('set_options', become_pass='password')
+
+    assert 'password' not in str(excinfo.value)