diff --git a/server-spi-private/src/main/java/org/keycloak/authentication/FormContext.java b/server-spi-private/src/main/java/org/keycloak/authentication/FormContext.java
index fb340ca640..f901af0979 100755
--- a/server-spi-private/src/main/java/org/keycloak/authentication/FormContext.java
+++ b/server-spi-private/src/main/java/org/keycloak/authentication/FormContext.java
@@ -58,7 +58,7 @@ public interface FormContext {
     AuthenticationExecutionModel getExecution();
 
     /**
-     * Current user attached to this flow.  It can return null if no uesr has been identified yet
+     * Current user attached to this flow.  It can return null if no user has been identified yet
      *
      * @return
      */
diff --git a/server-spi-private/src/main/java/org/keycloak/events/Errors.java b/server-spi-private/src/main/java/org/keycloak/events/Errors.java
index 1c021cd416..797a2e05c0 100755
--- a/server-spi-private/src/main/java/org/keycloak/events/Errors.java
+++ b/server-spi-private/src/main/java/org/keycloak/events/Errors.java
@@ -38,6 +38,7 @@ public interface Errors {
     String USER_DISABLED = "user_disabled";
     String USER_TEMPORARILY_DISABLED = "user_temporarily_disabled";
     String INVALID_USER_CREDENTIALS = "invalid_user_credentials";
+    String DIFFERENT_USER_AUTHENTICATING = "different_user_authenticating";
     String DIFFERENT_USER_AUTHENTICATED = "different_user_authenticated";
     String USER_DELETE_ERROR = "user_delete_error";
 
diff --git a/services/src/main/java/org/keycloak/authentication/forms/RegistrationUserCreation.java b/services/src/main/java/org/keycloak/authentication/forms/RegistrationUserCreation.java
index 84b33afd42..e1b583592a 100755
--- a/services/src/main/java/org/keycloak/authentication/forms/RegistrationUserCreation.java
+++ b/services/src/main/java/org/keycloak/authentication/forms/RegistrationUserCreation.java
@@ -18,6 +18,8 @@
 package org.keycloak.authentication.forms;
 
 import org.keycloak.Config;
+import org.keycloak.authentication.AuthenticationFlowError;
+import org.keycloak.authentication.AuthenticationFlowException;
 import org.keycloak.authentication.FormAction;
 import org.keycloak.authentication.FormActionFactory;
 import org.keycloak.authentication.FormContext;
@@ -106,11 +108,13 @@ public class RegistrationUserCreation implements FormAction, FormActionFactory {
 
     @Override
     public void buildPage(FormContext context, LoginFormsProvider form) {
-
+        checkNotOtherUserAuthenticating(context);
     }
 
     @Override
     public void success(FormContext context) {
+        checkNotOtherUserAuthenticating(context);
+
         MultivaluedMap<String, String> formData = context.getHttpRequest().getDecodedFormParameters();
 
         String email = formData.getFirst(UserModel.EMAIL);
@@ -148,6 +152,14 @@ public class RegistrationUserCreation implements FormAction, FormActionFactory {
         }
     }
 
+    private void checkNotOtherUserAuthenticating(FormContext context) {
+        if (context.getUser() != null) {
+            // the user probably did some back navigation in the browser, hitting this page in a strange state
+            context.getEvent().detail(Details.EXISTING_USER, context.getUser().getUsername());
+            throw new AuthenticationFlowException(AuthenticationFlowError.GENERIC_AUTHENTICATION_ERROR, Errors.DIFFERENT_USER_AUTHENTICATING, Messages.EXPIRED_ACTION);
+        }
+    }
+
     @Override
     public boolean requiresUser() {
         return false;
diff --git a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/forms/RegisterTest.java b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/forms/RegisterTest.java
index cff5c589f6..25115aad02 100644
--- a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/forms/RegisterTest.java
+++ b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/forms/RegisterTest.java
@@ -30,17 +30,20 @@ import org.keycloak.authentication.forms.RegistrationRecaptcha;
 import org.keycloak.authentication.forms.RegistrationTermsAndConditions;
 import org.keycloak.authentication.forms.RegistrationUserCreation;
 import org.keycloak.events.Details;
+import org.keycloak.events.Errors;
 import org.keycloak.events.EventType;
 import org.keycloak.models.AuthenticationExecutionModel;
+import org.keycloak.models.utils.DefaultAuthenticationFlows;
 import org.keycloak.representations.idm.EventRepresentation;
 import org.keycloak.representations.idm.RealmRepresentation;
 import org.keycloak.representations.idm.UserRepresentation;
 import org.keycloak.testsuite.AbstractTestRealmKeycloakTest;
 import org.keycloak.testsuite.AssertEvents;
-import org.keycloak.testsuite.AbstractTestRealmKeycloakTest;
 import org.keycloak.testsuite.pages.AppPage;
 import org.keycloak.testsuite.pages.AppPage.RequestType;
+import org.keycloak.testsuite.pages.ErrorPage;
 import org.keycloak.testsuite.pages.LoginPage;
+import org.keycloak.testsuite.pages.LoginPasswordResetPage;
 import org.keycloak.testsuite.pages.RegisterPage;
 import org.keycloak.testsuite.pages.VerifyEmailPage;
 import org.keycloak.testsuite.updaters.RealmAttributeUpdater;
@@ -79,12 +82,18 @@ public class RegisterTest extends AbstractTestRealmKeycloakTest {
     @Page
     protected LoginPage loginPage;
 
+    @Page
+    protected ErrorPage errorPage;
+
     @Page
     protected RegisterPage registerPage;
 
     @Page
     protected VerifyEmailPage verifyEmailPage;
 
+    @Page
+    protected LoginPasswordResetPage resetPasswordPage;
+
     @Rule
     public GreenMailRule greenMail = new GreenMailRule();
 
@@ -669,7 +678,7 @@ public class RegisterTest extends AbstractTestRealmKeycloakTest {
                     .removeDetail(Details.EMAIL)
                     .error("invalid_registration").assertEvent();
         } finally {
-            configureRegistrationFlowWithCustomRegistrationPageForm(UUID.randomUUID().toString());
+            revertRegistrationFlow();
         }
     }
 
@@ -697,6 +706,34 @@ public class RegisterTest extends AbstractTestRealmKeycloakTest {
         }
     }
 
+    @Test
+    public void testRegisterShouldFailBeforeUserCreationWhenUserIsInContext() {
+        loginPage.open();
+        loginPage.clickRegister();
+        registerPage.clickBackToLogin();
+        loginPage.assertCurrent(testRealm().toRepresentation().getRealm());
+
+        loginPage.resetPassword();
+        resetPasswordPage.assertCurrent();
+        resetPasswordPage.changePassword("test-user@localhost");
+
+        driver.navigate().back();
+        driver.navigate().back();
+        events.clear();
+        driver.navigate().back();
+
+        errorPage.assertCurrent();
+        Assert.assertEquals("Action expired. Please continue with login now.", errorPage.getError());
+
+        events.expectRegister("registerUserMissingTermsAcceptance", "registerUserMissingTermsAcceptance@email")
+                .removeDetail(Details.USERNAME)
+                .removeDetail(Details.EMAIL)
+                .removeDetail(Details.REGISTER_METHOD)
+                .detail(Details.EXISTING_USER, "test-user@localhost")
+                .detail(Details.AUTHENTICATION_ERROR_DETAIL, Errors.DIFFERENT_USER_AUTHENTICATING)
+                .error(Errors.GENERIC_AUTHENTICATION_ERROR).assertEvent();
+    }
+
     protected RealmAttributeUpdater configureRealmRegistrationEmailAsUsername(final boolean value) {
         return getRealmAttributeUpdater().setRegistrationEmailAsUsername(value);
     }
@@ -784,4 +821,11 @@ public class RegisterTest extends AbstractTestRealmKeycloakTest {
         );
     }
 
+    private void revertRegistrationFlow() {
+        testingClient.server("test").run(session -> FlowUtil.inCurrentRealm(session)
+                .selectFlow(DefaultAuthenticationFlows.REGISTRATION_FLOW)
+                .defineAsRegistrationFlow()
+        );
+    }
+
 }