diff --git a/mlflow_oidc_auth/config.py b/mlflow_oidc_auth/config.py
index b33ff8c..b385778 100644
--- a/mlflow_oidc_auth/config.py
+++ b/mlflow_oidc_auth/config.py
@@ -58,4 +58,4 @@ def __init__(self):
                 app.logger.error(f"Cache module for {self.CACHE_TYPE} could not be imported.")
 
 
-config = AppConfig()
+config = AppConfig()
\ No newline at end of file
diff --git a/mlflow_oidc_auth/views/authentication.py b/mlflow_oidc_auth/views/authentication.py
index bd96eb3..9269789 100644
--- a/mlflow_oidc_auth/views/authentication.py
+++ b/mlflow_oidc_auth/views/authentication.py
@@ -3,7 +3,7 @@
 from flask import redirect, session, url_for, render_template
 
 import mlflow_oidc_auth.utils as utils
-from mlflow_oidc_auth.auth import get_oauth_instance
+from mlflow_oidc_auth.auth import get_oauth_instance, validate_token
 from mlflow_oidc_auth.app import app
 from mlflow_oidc_auth.config import config
 from mlflow_oidc_auth.user import create_user, populate_groups, update_user
@@ -48,7 +48,13 @@ def callback():
 
         user_groups = importlib.import_module(config.OIDC_GROUP_DETECTION_PLUGIN).get_user_groups(token["access_token"])
     else:
-        user_groups = token["userinfo"][config.OIDC_GROUPS_ATTRIBUTE]
+        group_attr = config.OIDC_GROUPS_ATTRIBUTE
+        user_info = token["userinfo"]
+        decoded_access_token = validate_token(token["access_token"])
+        if group_attr in decoded_access_token:
+            user_groups = decoded_access_token[group_attr]
+        if group_attr in user_info:
+            user_groups = user_info[group_attr]
 
     app.logger.debug(f"User groups: {user_groups}")