diff --git a/CHANGES.rst b/CHANGES.rst
index 470f70cf7..0d89c6d01 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -21,6 +21,10 @@ Unreleased
     the requested size in one ``read`` call. :issue:`2558`
 -   A cookie header that starts with ``=`` is treated as an empty key and discarded,
     rather than stripping the leading ``==``.
+-   Specify a maximum number of multipart parts, default 100, after
+    which a RequestEntityTooLarge exception is raised on parsing. The
+    mitigates a DOS attack whereby a larger number file/form parts are
+    sent resulting in a heavy parsing cost.
 
 
 Version 2.2.2
diff --git a/src/werkzeug/formparser.py b/src/werkzeug/formparser.py
index 10d58ca3f..820190be2 100644
--- a/src/werkzeug/formparser.py
+++ b/src/werkzeug/formparser.py
@@ -179,6 +179,10 @@ class FormDataParser:
     :param cls: an optional dict class to use.  If this is not specified
                        or `None` the default :class:`MultiDict` is used.
     :param silent: If set to False parsing errors will not be caught.
+    :param max_form_parts: the maximum number of parts to be accepted for the
+                           multipart data sent. If this is exceeded an
+                           :exc:`~exceptions.RequestEntityTooLarge` exception
+                           is raised.
     """
 
     def __init__(
@@ -190,6 +194,7 @@ def __init__(
         max_content_length: t.Optional[int] = None,
         cls: t.Optional[t.Type[MultiDict]] = None,
         silent: bool = True,
+        max_form_parts: t.Optional[int] = None,
     ) -> None:
         if stream_factory is None:
             stream_factory = default_stream_factory
@@ -205,6 +210,7 @@ def __init__(
 
         self.cls = cls
         self.silent = silent
+        self.max_form_parts = max_form_parts
 
     def get_parse_func(
         self, mimetype: str, options: t.Dict[str, str]
@@ -281,6 +287,7 @@ def _parse_multipart(
             self.errors,
             max_form_memory_size=self.max_form_memory_size,
             cls=self.cls,
+            max_form_parts=self.max_form_parts,
         )
         boundary = options.get("boundary", "").encode("ascii")
 
@@ -346,10 +353,12 @@ def __init__(
         max_form_memory_size: t.Optional[int] = None,
         cls: t.Optional[t.Type[MultiDict]] = None,
         buffer_size: int = 64 * 1024,
+        max_form_parts: t.Optional[int] = None,
     ) -> None:
         self.charset = charset
         self.errors = errors
         self.max_form_memory_size = max_form_memory_size
+        self.max_form_parts = max_form_parts
 
         if stream_factory is None:
             stream_factory = default_stream_factory
@@ -409,7 +418,9 @@ def parse(
             [None],
         )
 
-        parser = MultipartDecoder(boundary, self.max_form_memory_size)
+        parser = MultipartDecoder(
+            boundary, self.max_form_memory_size, self.max_form_parts
+        )
 
         fields = []
         files = []
diff --git a/src/werkzeug/sansio/multipart.py b/src/werkzeug/sansio/multipart.py
index d8abeb354..d90b445b9 100644
--- a/src/werkzeug/sansio/multipart.py
+++ b/src/werkzeug/sansio/multipart.py
@@ -87,10 +87,12 @@ def __init__(
         self,
         boundary: bytes,
         max_form_memory_size: Optional[int] = None,
+        max_parts: Optional[int] = None,
     ) -> None:
         self.buffer = bytearray()
         self.complete = False
         self.max_form_memory_size = max_form_memory_size
+        self.max_parts = max_parts
         self.state = State.PREAMBLE
         self.boundary = boundary
 
@@ -118,6 +120,7 @@ def __init__(
             re.MULTILINE,
         )
         self._search_position = 0
+        self._parts_decoded = 0
 
     def last_newline(self) -> int:
         try:
@@ -191,6 +194,10 @@ def next_event(self) -> Event:
                     )
                 self.state = State.DATA
                 self._search_position = 0
+                self._parts_decoded += 1
+
+                if self.max_parts is not None and self._parts_decoded > self.max_parts:
+                    raise RequestEntityTooLarge()
             else:
                 # Update the search start position to be equal to the
                 # current buffer length (already searched) minus a
diff --git a/src/werkzeug/wrappers/request.py b/src/werkzeug/wrappers/request.py
index 283e59229..fa5b18586 100644
--- a/src/werkzeug/wrappers/request.py
+++ b/src/werkzeug/wrappers/request.py
@@ -83,6 +83,16 @@ class Request(_SansIORequest):
     #: .. versionadded:: 0.5
     max_form_memory_size: t.Optional[int] = None
 
+    #: the maximum number of multipart parts. This is forwarded to teh
+    #: form data parsing function (:func:`parse_form_data`).  When the
+    #: :attr:`form` or :attr:`files` attribute is accessed and the
+    #: parsing fails because more parts than the specified value is
+    #: transmitted a :exc:`~werkzeug.exceptions.RequestEntityTooLarge`
+    #: exception is raised.
+    #:
+    #: .. versionadded:: 2.2.3
+    max_form_parts = 1000
+
     #: The form data parser that should be used.  Can be replaced to customize
     #: the form date parsing.
     form_data_parser_class: t.Type[FormDataParser] = FormDataParser
@@ -246,6 +256,7 @@ def make_form_data_parser(self) -> FormDataParser:
             self.max_form_memory_size,
             self.max_content_length,
             self.parameter_storage_class,
+            max_form_parts=self.max_form_parts,
         )
 
     def _load_form_data(self) -> None:
diff --git a/tests/test_formparser.py b/tests/test_formparser.py
index 49010b46c..4c518b14b 100644
--- a/tests/test_formparser.py
+++ b/tests/test_formparser.py
@@ -127,6 +127,15 @@ def test_limiting(self):
         req.max_form_memory_size = 400
         assert req.form["foo"] == "Hello World"
 
+        req = Request.from_values(
+            input_stream=io.BytesIO(data),
+            content_length=len(data),
+            content_type="multipart/form-data; boundary=foo",
+            method="POST",
+        )
+        req.max_form_parts = 1
+        pytest.raises(RequestEntityTooLarge, lambda: req.form["foo"])
+
     def test_missing_multipart_boundary(self):
         data = (
             b"--foo\r\nContent-Disposition: form-field; name=foo\r\n\r\n"