Harden backend against critical and high security vulnerabilities

- Fix WebSocket CheckOrigin to use proper url.Parse instead of string stripping
- Add admin auth checks to Users/User GraphQL queries
- Remove GraphQL GET transport to prevent CSRF via cross-site links
- Add application-level IP-based login rate limiting (5 attempts/min)
- Add path traversal bounds check on radio file upload
- Require DEV_MODE for GraphQL introspection and playground
- Move notes backend endpoint behind admin middleware
- Add dedicated Nginx rate limit zone for GraphQL (10r/s)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/graph/schema.resolvers.go

@@ -25,6 +25,10 @@ func (r *mutationResolver) Login(ctx context.Context, input model.LoginInput) (*
 		return nil, fmt.Errorf("could not get gin context")
 	}
 
+	if !r.Store.LoginLimiter.Allow(gc.ClientIP()) {
+		return nil, fmt.Errorf("too many login attempts, please try again later")
+	}
+
 	var user models.User
 	if err := r.Store.DB.Where("username = ?", input.Username).First(&user).Error; err != nil {
 		return nil, fmt.Errorf("invalid credentials")
@@ -446,6 +450,9 @@ func (r *mutationResolver) DeleteJobAppReference(ctx context.Context, id int) (b
 
 // Users is the resolver for the users field.
 func (r *queryResolver) Users(ctx context.Context) ([]*models.User, error) {
+	if !IsAdminFromCtx(ctx) {
+		return nil, fmt.Errorf("admin access required")
+	}
 	var users []models.User
 	if err := r.Store.DB.Find(&users).Error; err != nil {
 		return nil, err
@@ -459,6 +466,9 @@ func (r *queryResolver) Users(ctx context.Context) ([]*models.User, error) {
 
 // User is the resolver for the user field.
 func (r *queryResolver) User(ctx context.Context, id int) (*models.User, error) {
+	if !IsAdminFromCtx(ctx) {
+		return nil, fmt.Errorf("admin access required")
+	}
 	var user models.User
 	if err := r.Store.DB.First(&user, id).Error; err != nil {
 		return nil, fmt.Errorf("user not found")

backend/handlers/handle_auth.go

@@ -226,6 +226,11 @@ func (store *Store) RefreshToken(ctx *gin.Context) {
 }
 
 func (store *Store) Login(ctx *gin.Context) {
+	if !store.LoginLimiter.Allow(ctx.ClientIP()) {
+		ctx.JSON(http.StatusTooManyRequests, gin.H{"error": "too many login attempts, please try again later"})
+		return
+	}
+
 	var input UserCredentials
 	if err := ctx.ShouldBindBodyWithJSON(&input); err != nil {
 		ctx.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body"})

backend/handlers/handle_radio.go

@@ -37,6 +37,13 @@ func (store *Store) UploadRadioSong(ctx *gin.Context) {
 	filename := filepath.Base(file.Filename)
 	dest := filepath.Join(fallbackMusicDir, filename)
 
+	// Verify the resolved path stays within the music directory
+	absDest, err := filepath.Abs(dest)
+	if err != nil || !strings.HasPrefix(absDest, fallbackMusicDir+string(os.PathSeparator)) {
+		ctx.JSON(http.StatusBadRequest, gin.H{"error": "invalid filename"})
+		return
+	}
+
 	if _, err := os.Stat(dest); err == nil {
 		ctx.JSON(http.StatusConflict, gin.H{"error": "file already exists"})
 		return

backend/handlers/store.go

@@ -17,6 +17,7 @@ type Store struct {
 	ClaudeClient  *anthropic.Client
 	Auth          *services.Auth
 	Notes         *services.Notes
+	LoginLimiter  *services.RateLimiter
 
 	RecentSongs          *[]spotify.RecentlyPlayedItem
 	RecentSongsFetchedAt time.Time

backend/main.go

@@ -85,7 +85,9 @@ func main() {
 	steamAPIKey := os.Getenv("STEAM_API_KEY")
 	steamID := os.Getenv("STEAM_ID")
 
-	store := handlers.Store{DB: db, SpotifyAuth: spotifyAuth, SpotifyClient: spotifyClient, ClaudeClient: claudeClient, Auth: auth, Notes: notes, GiteaHost: giteaHost, GiteaPort: giteaPort, SteamAPIKey: steamAPIKey, SteamID: steamID}
+	loginLimiter := services.NewRateLimiter(5, time.Minute)
+
+	store := handlers.Store{DB: db, SpotifyAuth: spotifyAuth, SpotifyClient: spotifyClient, ClaudeClient: claudeClient, Auth: auth, Notes: notes, LoginLimiter: loginLimiter, GiteaHost: giteaHost, GiteaPort: giteaPort, SteamAPIKey: steamAPIKey, SteamID: steamID}
 
 	protected := r.Group("/", store.AuthMiddlewear)
 	admin := r.Group("/", store.AuthMiddlewear, store.AdminMiddleware)
@@ -119,7 +121,7 @@ func main() {
 	protected.POST("/messages/upload", store.UploadMessageFile)
 
 	// NOTES
-	r.GET("/notes/*path", store.GetNoteFile)
+	admin.GET("/notes/*path", store.GetNoteFile)
 
 	// GRAPHQL
 	gqlSrv := handler.New(graph.NewExecutableSchema(graph.Config{
@@ -127,18 +129,18 @@ func main() {
 	}))
 	gqlSrv.AddTransport(transport.Websocket{KeepAlivePingInterval: 10 * time.Second})
 	gqlSrv.AddTransport(transport.Options{})
-	gqlSrv.AddTransport(transport.GET{})
 	gqlSrv.AddTransport(transport.POST{})
 	gqlSrv.AddTransport(transport.MultipartForm{})
 	gqlSrv.SetQueryCache(lru.New[*ast.QueryDocument](1000))
 	gqlSrv.Use(extension.FixedComplexityLimit(200))
-	if os.Getenv("GQL_INTROSPECTION") == "true" {
+	devMode := os.Getenv("DEV_MODE") == "true"
+	if devMode && os.Getenv("GQL_INTROSPECTION") == "true" {
 		gqlSrv.Use(extension.Introspection{})
 	}
 	r.POST("/graphql", graph.AuthContextMiddleware(auth), func(c *gin.Context) {
 		gqlSrv.ServeHTTP(c.Writer, c.Request)
 	})
-	if os.Getenv("GQL_PLAYGROUND") == "true" {
+	if devMode && os.Getenv("GQL_PLAYGROUND") == "true" {
 		r.GET("/graphql", func(c *gin.Context) {
 			playground.Handler("GraphQL Playground", "/graphql").ServeHTTP(c.Writer, c.Request)
 		})

backend/services/ratelimit.go

@@ -0,0 +1,45 @@
+package services
+
+import (
+	"sync"
+	"time"
+)
+
+type RateLimiter struct {
+	mu       sync.Mutex
+	attempts map[string][]time.Time
+	max      int
+	window   time.Duration
+}
+
+func NewRateLimiter(max int, window time.Duration) *RateLimiter {
+	return &RateLimiter{
+		attempts: make(map[string][]time.Time),
+		max:      max,
+		window:   window,
+	}
+}
+
+func (rl *RateLimiter) Allow(key string) bool {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	now := time.Now()
+	cutoff := now.Add(-rl.window)
+
+	// Remove expired entries
+	valid := rl.attempts[key][:0]
+	for _, t := range rl.attempts[key] {
+		if t.After(cutoff) {
+			valid = append(valid, t)
+		}
+	}
+
+	if len(valid) >= rl.max {
+		rl.attempts[key] = valid
+		return false
+	}
+
+	rl.attempts[key] = append(valid, now)
+	return true
+}

backend/services/websocket.go

@@ -2,7 +2,7 @@ package services
 
 import (
 	"net/http"
-	"strings"
+	"net/url"
 	"sync"
 	"time"
 
@@ -24,11 +24,12 @@ var Upgrader = websocket.Upgrader{
 		if origin == "" {
 			return false
 		}
-		origin = strings.TrimPrefix(origin, "https://")
+		u, err := url.Parse(origin)
-		origin = strings.TrimPrefix(origin, "http://")
+		if err != nil {
-		// Strip port for localhost comparisons (e.g. "localhost:80")
+			return false
-		host := strings.Split(origin, ":")[0]
+		}
-		return origin == allowedDomain || origin == "www."+allowedDomain || host == "localhost"
+		host := u.Hostname()
+		return host == allowedDomain || host == "www."+allowedDomain || host == "localhost"
 	},
 }
 

nginx/nginx.conf.template

@@ -13,6 +13,7 @@ http {
 
     limit_req_zone $binary_remote_addr zone=login:10m rate=5r/m;
     limit_req_zone $binary_remote_addr zone=api:10m rate=30r/s;
+    limit_req_zone $binary_remote_addr zone=graphql:10m rate=10r/s;
     limit_req_zone $binary_remote_addr zone=upload:10m rate=5r/m;
 
     log_format compact
@@ -168,6 +169,16 @@ http {
             proxy_set_header X-Forwarded-Proto $scheme;
         }
 
+        location $BACKEND_ENDPOINT/graphql {
+            limit_req zone=graphql burst=10 nodelay;
+            rewrite ^$BACKEND_ENDPOINT/(.*)$ /$1 break;
+            proxy_pass http://$BACKEND_HOST:$BACKEND_PORT/;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+        }
+
         location $BACKEND_ENDPOINT/ {
             limit_req zone=api burst=20 nodelay;
             rewrite ^$BACKEND_ENDPOINT/(.*)$ /$1 break;