fix(security): apply user label filter to notification preview (#4950)

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/web/notifications.go

@@ -569,7 +569,7 @@ func (h *handler) previewExpression(w http.ResponseWriter, r *http.Request) {
 
 	// Find matching running containers
 	if sub.ContainerProgram != nil {
-		containers, _ := h.hostService.ListAllContainers(container.ContainerLabels{})
+		containers, _ := h.hostService.ListAllContainers(h.resolveLabels(r))
 		for _, c := range containers {
 			if c.State != "running" {
 				continue
@@ -592,7 +592,7 @@ func (h *handler) previewExpression(w http.ResponseWriter, r *http.Request) {
 		keySet := make(map[string]struct{})
 
 		for _, c := range result.MatchedContainers {
-			containerService, err := h.hostService.FindContainer(c.Host, c.ID, container.ContainerLabels{})
+			containerService, err := h.hostService.FindContainer(c.Host, c.ID, h.resolveLabels(r))
 			if err != nil {
 				continue
 			}

internal/web/notifications_test.go

@@ -0,0 +1,62 @@
+package web
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/amir20/dozzle/internal/auth"
+	"github.com/amir20/dozzle/internal/container"
+	docker_support "github.com/amir20/dozzle/internal/support/docker"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+// Test_previewExpression_respects_user_labels makes sure the notification preview endpoint
+// only enumerates containers within the caller's label scope. See GHSA-r9cj-7m9r-h6hq.
+func Test_previewExpression_respects_user_labels(t *testing.T) {
+	dev := container.Container{ID: "dev123", Name: "dev-allowed", State: "running", Labels: map[string]string{"env": "dev"}}
+	prod := container.Container{ID: "prod456", Name: "prod-secret", State: "running", Labels: map[string]string{"env": "prod"}}
+	userLabels := container.ContainerLabels{"env": []string{"dev"}}
+
+	client := new(MockedClient)
+	client.On("Host").Return(container.Host{ID: "localhost"})
+	client.On("ContainerEvents", mock.Anything, mock.AnythingOfType("chan<- container.ContainerEvent")).Return(nil)
+	client.On("ListContainers", mock.Anything, userLabels).Return([]container.Container{dev}, nil)
+	client.On("ListContainers", mock.Anything, mock.Anything).Return([]container.Container{dev, prod}, nil)
+	client.On("FindContainer", mock.Anything, "dev123").Return(dev, nil)
+	client.On("FindContainer", mock.Anything, "prod456").Return(prod, nil)
+	client.On("ContainerLogsBetweenDates", mock.Anything, mock.Anything, mock.Anything, mock.Anything, mock.Anything).
+		Return(io.NopCloser(strings.NewReader("")), nil)
+
+	manager := docker_support.NewRetriableClientManager(nil, 3*time.Second, tls.Certificate{}, docker_support.NewDockerClientService(client, container.ContainerLabels{}))
+	h := &handler{
+		hostService: docker_support.NewMultiHostService(manager, 3*time.Second),
+		config:      &Config{Base: "/", Authorization: Authorization{Provider: SIMPLE}},
+	}
+
+	body := strings.NewReader(`{"containerExpression":"true","logExpression":"true"}`)
+	req := httptest.NewRequest("POST", "/api/notifications/preview", body)
+	req = req.WithContext(auth.WithUser(context.Background(), auth.User{ContainerLabels: userLabels}))
+	rr := httptest.NewRecorder()
+
+	h.previewExpression(rr, req)
+
+	require.Equal(t, http.StatusOK, rr.Code)
+
+	var result PreviewResult
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &result))
+
+	names := make([]string, 0, len(result.MatchedContainers))
+	for _, c := range result.MatchedContainers {
+		names = append(names, c.Name)
+	}
+	assert.Equal(t, []string{"dev-allowed"}, names, "preview should not leak out-of-scope containers")
+}