diff --git a/keystoneauth_websso/plugin.py b/keystoneauth_websso/plugin.py
index 5e56ff1..9a89419 100644
--- a/keystoneauth_websso/plugin.py
+++ b/keystoneauth_websso/plugin.py
@@ -15,7 +15,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import cgi
 import json
 import os
 import re
@@ -24,6 +23,7 @@
 from datetime import datetime
 from http.server import BaseHTTPRequestHandler, HTTPServer
 
+import multipart
 from keystoneauth1 import _utils as utils
 from keystoneauth1.identity.v3 import federation
 
@@ -75,14 +75,13 @@ def do_POST(self):
 
         if self.headers:
 
-            form = cgi.FieldStorage(
-                fp=self.rfile,
-                headers=self.headers,
-                environ={
-                    "REQUEST_METHOD": "POST",
-                    "CONTENT_TYPE": self.headers["Content-Type"],
-                },
-            )
+            environ = {
+                "REQUEST_METHOD": "POST",
+                "CONTENT_LENGTH": self.headers["Content-Length"],
+                "CONTENT_TYPE": self.headers["Content-Type"],
+                "wsgi.input": self.rfile,
+            }
+            forms, files = multipart.parse_form_data(environ)
 
             self.send_response(200)
             self.send_header("Content-type", "text/html")
@@ -95,11 +94,8 @@ def do_POST(self):
                 b"</body></html>"
             )
 
-            for field in form.keys():
-                field_item = form[field]
-                if not field_item.filename:
-                    # Regular Form Value
-                    postvars[field] = form[field].value
+            for field, value in forms.items():
+                postvars[field] = value
 
             self.server.token = postvars["token"]
         else:
diff --git a/poetry.lock b/poetry.lock
index 466e4c6..72076df 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 1.7.1 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.8.3 and should not be changed by hand.
 
 [[package]]
 name = "certifi"
@@ -157,6 +157,20 @@ oauth1 = ["oauthlib (>=0.6.2)"]
 saml2 = ["lxml (>=4.2.0)"]
 test = ["PyYAML (>=3.12)", "bandit (>=1.7.6,<1.8.0)", "betamax (>=0.7.0)", "coverage (>=4.0,!=4.4)", "fixtures (>=3.0.0)", "flake8-docstrings (>=1.7.0,<1.8.0)", "flake8-import-order (>=0.18.2,<0.19.0)", "hacking (>=6.1.0,<6.2.0)", "lxml (>=4.2.0)", "oauthlib (>=0.6.2)", "oslo.config (>=5.2.0)", "oslo.utils (>=3.33.0)", "oslotest (>=3.2.0)", "reno (>=3.1.0)", "requests-kerberos (>=0.8.0)", "requests-mock (>=1.2.0)", "stestr (>=1.0.0)", "testresources (>=2.0.0)", "testtools (>=2.2.0)"]
 
+[[package]]
+name = "multipart"
+version = "1.1.0"
+description = "Parser for multipart/form-data"
+optional = false
+python-versions = ">=3.5"
+files = [
+    {file = "multipart-1.1.0-py3-none-any.whl", hash = "sha256:5a784677de8b49e6409e730dfe018f73c5d7aef360e44750e00f67d669b51e91"},
+    {file = "multipart-1.1.0.tar.gz", hash = "sha256:ee32683f5c454740cd9139e1d6057053823da0729c426f156464f81111529ba1"},
+]
+
+[package.extras]
+dev = ["build", "pytest", "pytest-cov", "twine"]
+
 [[package]]
 name = "os-service-types"
 version = "1.7.0"
@@ -237,4 +251,4 @@ zstd = ["zstandard (>=0.18.0)"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.8"
-content-hash = "34d783c776ac0004b36fd200cea954183d7269e6eb6bf022a0187af5df994a00"
+content-hash = "1e6953215db1cf8cfcdc092f4adb6264454e2352226c66891ffaa68e16821563"
diff --git a/pyproject.toml b/pyproject.toml
index 597e115..b4728a8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,10 +19,11 @@ classifiers = [
 [tool.poetry.dependencies]
 python = "^3.8"
 keystoneauth1 = ">=5.0.0"
+multipart = ">=1.0.0"
 
 [build-system]
 requires = ["poetry-core"]
 build-backend = "poetry.core.masonry.api"
 
 [tool.poetry.plugins."keystoneauth1.plugin"]
-v3websso = "keystoneauth_websso.loading:OpenIDConnect"
\ No newline at end of file
+v3websso = "keystoneauth_websso.loading:OpenIDConnect"