diff --git a/services/src/main/java/org/keycloak/broker/oidc/OIDCIdentityProvider.java b/services/src/main/java/org/keycloak/broker/oidc/OIDCIdentityProvider.java
index e12e49f1de..086b491476 100755
--- a/services/src/main/java/org/keycloak/broker/oidc/OIDCIdentityProvider.java
+++ b/services/src/main/java/org/keycloak/broker/oidc/OIDCIdentityProvider.java
@@ -102,6 +102,14 @@ public class OIDCIdentityProvider extends AbstractOAuth2IdentityProvider<OIDCIde
         @GET
         @Path("logout_response")
         public Response logoutResponse(@QueryParam("state") String state) {
+            if (state == null){
+                logger.error("no state parameter returned");
+                EventBuilder event = new EventBuilder(realm, session, clientConnection);
+                event.event(EventType.LOGOUT);
+                event.error(Errors.USER_SESSION_NOT_FOUND);
+                return ErrorPage.error(session, null, Response.Status.BAD_REQUEST, Messages.IDENTITY_PROVIDER_UNEXPECTED_ERROR);
+            
+            }
             UserSessionModel userSession = session.sessions().getUserSession(realm, state);
             if (userSession == null) {
                 logger.error("no valid user session");