fix(mfa): refuse rather than panic when RequireStepUp sees no session

server/internal/auth/stepup.go

@@ -41,6 +41,10 @@ func RequireStepUp() gin.HandlerFunc {
 			c.Next()
 			return
 		}
+		if sess == nil {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "not authenticated"})
+			return
+		}
 		methods, err := services.MFAMethods(sess.InstanceID, sess.UserID)
 		if err != nil || len(methods) == 0 {
 			methods = []string{services.FactorPassword}

server/internal/auth/stepup_test.go

@@ -1,8 +1,12 @@
 package auth
 
 import (
+	"net/http"
+	"net/http/httptest"
 	"testing"
 	"time"
+
+	"github.com/gin-gonic/gin"
 )
 
 func TestStepUpFresh(t *testing.T) {
@@ -32,3 +36,19 @@ func TestStepUpFresh(t *testing.T) {
 		})
 	}
 }
+
+// A missing session must refuse rather than panic dereferencing sess.
+// auth.Middleware guarantees a non-nil session on every route today, but
+// RequireStepUp must not rely on that holding forever.
+func TestRequireStepUpNilSessionRefusesWithoutPanic(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Request = httptest.NewRequest(http.MethodPost, "/console/connect", nil)
+
+	RequireStepUp()(c)
+
+	if w.Code != http.StatusUnauthorized {
+		t.Fatalf("status = %d, want %d", w.Code, http.StatusUnauthorized)
+	}
+}