diff --git a/pkg/mining/manager.go b/pkg/mining/manager.go
index a95b558..28bdc55 100644
--- a/pkg/mining/manager.go
+++ b/pkg/mining/manager.go
@@ -34,6 +34,7 @@ type Manager struct {
 	miners      map[string]Miner
 	mu          sync.RWMutex
 	stopChan    chan struct{}
+	stopOnce    sync.Once
 	waitGroup   sync.WaitGroup
 	dbEnabled   bool
 	dbRetention int
@@ -505,25 +506,28 @@ func (m *Manager) GetMinerHashrateHistory(name string) ([]HashratePoint, error)
 }
 
 // Stop stops all running miners, background goroutines, and closes resources.
+// Safe to call multiple times - subsequent calls are no-ops.
 func (m *Manager) Stop() {
-	// Stop all running miners first
-	m.mu.Lock()
-	for name, miner := range m.miners {
-		if err := miner.Stop(); err != nil {
-			log.Printf("Warning: failed to stop miner %s: %v", name, err)
+	m.stopOnce.Do(func() {
+		// Stop all running miners first
+		m.mu.Lock()
+		for name, miner := range m.miners {
+			if err := miner.Stop(); err != nil {
+				log.Printf("Warning: failed to stop miner %s: %v", name, err)
+			}
 		}
-	}
-	m.mu.Unlock()
+		m.mu.Unlock()
 
-	close(m.stopChan)
-	m.waitGroup.Wait()
+		close(m.stopChan)
+		m.waitGroup.Wait()
 
-	// Close the database
-	if m.dbEnabled {
-		if err := database.Close(); err != nil {
-			log.Printf("Warning: failed to close database: %v", err)
+		// Close the database
+		if m.dbEnabled {
+			if err := database.Close(); err != nil {
+				log.Printf("Warning: failed to close database: %v", err)
+			}
 		}
-	}
+	})
 }
 
 // GetMinerHistoricalStats returns historical stats from the database for a miner.
diff --git a/pkg/mining/miner.go b/pkg/mining/miner.go
index 62c8933..51f5e74 100644
--- a/pkg/mining/miner.go
+++ b/pkg/mining/miner.go
@@ -39,6 +39,9 @@ func NewLogBuffer(maxLines int) *LogBuffer {
 	}
 }
 
+// maxLineLength is the maximum length of a single log line to prevent memory bloat.
+const maxLineLength = 2000
+
 // Write implements io.Writer for capturing output.
 func (lb *LogBuffer) Write(p []byte) (n int, err error) {
 	lb.mu.Lock()
@@ -52,13 +55,19 @@ func (lb *LogBuffer) Write(p []byte) (n int, err error) {
 		if line == "" {
 			continue
 		}
+		// Truncate excessively long lines to prevent memory bloat
+		if len(line) > maxLineLength {
+			line = line[:maxLineLength] + "... [truncated]"
+		}
 		// Add timestamp prefix
 		timestampedLine := fmt.Sprintf("[%s] %s", time.Now().Format("15:04:05"), line)
 		lb.lines = append(lb.lines, timestampedLine)
 
-		// Trim if over max
+		// Trim if over max - force reallocation to release memory
 		if len(lb.lines) > lb.maxLines {
-			lb.lines = lb.lines[len(lb.lines)-lb.maxLines:]
+			newSlice := make([]string, lb.maxLines)
+			copy(newSlice, lb.lines[len(lb.lines)-lb.maxLines:])
+			lb.lines = newSlice
 		}
 	}
 	return len(p), nil
@@ -225,6 +234,8 @@ func (b *BaseMiner) InstallFromURL(url string) error {
 	}
 
 	if _, err := io.Copy(tmpfile, resp.Body); err != nil {
+		// Drain remaining body to allow connection reuse
+		io.Copy(io.Discard, resp.Body)
 		return err
 	}
 
@@ -438,7 +449,14 @@ func (b *BaseMiner) ReduceHashrateHistory(now time.Time) {
 			newHighResHistory = append(newHighResHistory, p)
 		}
 	}
-	b.HashrateHistory = newHighResHistory
+	// Force reallocation if significantly oversized to free memory
+	if cap(b.HashrateHistory) > 1000 && len(newHighResHistory) < cap(b.HashrateHistory)/2 {
+		trimmed := make([]HashratePoint, len(newHighResHistory))
+		copy(trimmed, newHighResHistory)
+		b.HashrateHistory = trimmed
+	} else {
+		b.HashrateHistory = newHighResHistory
+	}
 
 	if len(pointsToAggregate) == 0 {
 		b.LastLowResAggregation = now
@@ -480,7 +498,16 @@ func (b *BaseMiner) ReduceHashrateHistory(now time.Time) {
 			firstValidLowResIndex = len(b.LowResHashrateHistory)
 		}
 	}
-	b.LowResHashrateHistory = b.LowResHashrateHistory[firstValidLowResIndex:]
+
+	// Force reallocation if significantly oversized to free memory
+	newLowResLen := len(b.LowResHashrateHistory) - firstValidLowResIndex
+	if cap(b.LowResHashrateHistory) > 1000 && newLowResLen < cap(b.LowResHashrateHistory)/2 {
+		trimmed := make([]HashratePoint, newLowResLen)
+		copy(trimmed, b.LowResHashrateHistory[firstValidLowResIndex:])
+		b.LowResHashrateHistory = trimmed
+	} else {
+		b.LowResHashrateHistory = b.LowResHashrateHistory[firstValidLowResIndex:]
+	}
 	b.LastLowResAggregation = now
 }
 
diff --git a/pkg/mining/service.go b/pkg/mining/service.go
index 6151a31..743b7f0 100644
--- a/pkg/mining/service.go
+++ b/pkg/mining/service.go
@@ -68,7 +68,11 @@ func NewService(manager ManagerInterface, listenAddr string, displayAddr string,
 		ProfileManager: profileManager,
 		NodeService:    nodeService,
 		Server: &http.Server{
-			Addr: listenAddr,
+			Addr:              listenAddr,
+			ReadTimeout:       30 * time.Second,
+			WriteTimeout:      30 * time.Second,
+			IdleTimeout:       60 * time.Second,
+			ReadHeaderTimeout: 10 * time.Second,
 		},
 		DisplayAddr:         displayAddr,
 		SwaggerInstanceName: instanceName,
@@ -83,6 +87,14 @@ func NewService(manager ManagerInterface, listenAddr string, displayAddr string,
 func (s *Service) InitRouter() {
 	s.Router = gin.Default()
 
+	// Extract port safely from server address for CORS
+	serverPort := "9090" // default fallback
+	if s.Server.Addr != "" {
+		if _, port, err := net.SplitHostPort(s.Server.Addr); err == nil && port != "" {
+			serverPort = port
+		}
+	}
+
 	// Configure CORS to only allow local origins
 	corsConfig := cors.Config{
 		AllowOrigins: []string{
@@ -90,8 +102,8 @@ func (s *Service) InitRouter() {
 			"http://127.0.0.1:4200",
 			"http://localhost:9090",  // Default API port
 			"http://127.0.0.1:9090",
-			"http://localhost:" + strings.Split(s.Server.Addr, ":")[len(strings.Split(s.Server.Addr, ":"))-1],
-			"http://127.0.0.1:" + strings.Split(s.Server.Addr, ":")[len(strings.Split(s.Server.Addr, ":"))-1],
+			"http://localhost:" + serverPort,
+			"http://127.0.0.1:" + serverPort,
 			"wails://wails",          // Wails desktop app
 		},
 		AllowMethods:     []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
@@ -101,6 +113,13 @@ func (s *Service) InitRouter() {
 		MaxAge:           12 * time.Hour,
 	}
 	s.Router.Use(cors.New(corsConfig))
+
+	// Add request body size limit middleware (1MB max)
+	s.Router.Use(func(c *gin.Context) {
+		c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, 1<<20) // 1MB
+		c.Next()
+	})
+
 	s.SetupRoutes()
 }
 
diff --git a/pkg/mining/ttminer_start.go b/pkg/mining/ttminer_start.go
index f39887c..20ba909 100644
--- a/pkg/mining/ttminer_start.go
+++ b/pkg/mining/ttminer_start.go
@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"time"
 )
 
 // Start launches the TT-Miner with the given configuration.
@@ -67,7 +68,26 @@ func (m *TTMiner) Start(config *Config) error {
 	// Capture cmd locally to avoid race with Stop()
 	cmd := m.cmd
 	go func() {
-		err := cmd.Wait()
+		// Use a channel to detect if Wait() completes
+		done := make(chan error, 1)
+		go func() {
+			done <- cmd.Wait()
+		}()
+
+		// Wait with timeout to prevent goroutine leak on zombie processes
+		var err error
+		select {
+		case err = <-done:
+			// Normal exit
+		case <-time.After(5 * time.Minute):
+			// Process didn't exit after 5 minutes - force cleanup
+			log.Printf("TT-Miner process wait timeout, forcing cleanup")
+			if cmd.Process != nil {
+				cmd.Process.Kill()
+			}
+			err = <-done // Wait for the inner goroutine to finish
+		}
+
 		m.mu.Lock()
 		// Only clear if this is still the same command (not restarted)
 		if m.cmd == cmd {
diff --git a/pkg/mining/xmrig_start.go b/pkg/mining/xmrig_start.go
index 1e07067..e757e9c 100644
--- a/pkg/mining/xmrig_start.go
+++ b/pkg/mining/xmrig_start.go
@@ -10,6 +10,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
+	"time"
 )
 
 // Start launches the XMRig miner with the specified configuration.
@@ -90,7 +91,26 @@ func (m *XMRigMiner) Start(config *Config) error {
 	// Capture cmd locally to avoid race with Stop()
 	cmd := m.cmd
 	go func() {
-		cmd.Wait()
+		// Use a channel to detect if Wait() completes
+		done := make(chan struct{})
+		go func() {
+			cmd.Wait()
+			close(done)
+		}()
+
+		// Wait with timeout to prevent goroutine leak on zombie processes
+		select {
+		case <-done:
+			// Normal exit
+		case <-time.After(5 * time.Minute):
+			// Process didn't exit after 5 minutes - force cleanup
+			log.Printf("Miner process wait timeout, forcing cleanup")
+			if cmd.Process != nil {
+				cmd.Process.Kill()
+			}
+			<-done // Wait for the inner goroutine to finish
+		}
+
 		m.mu.Lock()
 		// Only clear if this is still the same command (not restarted)
 		if m.cmd == cmd {
diff --git a/pkg/node/controller.go b/pkg/node/controller.go
index 8b5dbd0..15e571a 100644
--- a/pkg/node/controller.go
+++ b/pkg/node/controller.go
@@ -83,11 +83,12 @@ func (c *Controller) sendRequest(peerID string, msg *Message, timeout time.Durat
 	c.pending[msg.ID] = respCh
 	c.mu.Unlock()
 
-	// Clean up on exit
+	// Clean up on exit - ensure channel is closed and removed from map
 	defer func() {
 		c.mu.Lock()
 		delete(c.pending, msg.ID)
 		c.mu.Unlock()
+		close(respCh) // Close channel to allow garbage collection
 	}()
 
 	// Send the message
@@ -341,6 +342,9 @@ func (c *Controller) GetTotalHashrate() float64 {
 	var total float64
 
 	for _, stats := range allStats {
+		if stats == nil {
+			continue
+		}
 		for _, miner := range stats.Miners {
 			total += miner.Hashrate
 		}
diff --git a/pkg/node/transport.go b/pkg/node/transport.go
index d838e4f..5337c0f 100644
--- a/pkg/node/transport.go
+++ b/pkg/node/transport.go
@@ -77,7 +77,20 @@ func NewTransport(node *NodeManager, registry *PeerRegistry, config TransportCon
 		upgrader: websocket.Upgrader{
 			ReadBufferSize:  1024,
 			WriteBufferSize: 1024,
-			CheckOrigin:     func(r *http.Request) bool { return true }, // Allow all origins
+			CheckOrigin: func(r *http.Request) bool {
+				// Allow local connections only for security
+				origin := r.Header.Get("Origin")
+				if origin == "" {
+					return true // No origin header (non-browser client)
+				}
+				// Allow localhost and 127.0.0.1 origins
+				u, err := url.Parse(origin)
+				if err != nil {
+					return false
+				}
+				host := u.Hostname()
+				return host == "localhost" || host == "127.0.0.1" || host == "::1"
+			},
 		},
 		ctx:    ctx,
 		cancel: cancel,
@@ -238,6 +251,16 @@ func (t *Transport) GetConnection(peerID string) *PeerConnection {
 
 // handleWSUpgrade handles incoming WebSocket connections.
 func (t *Transport) handleWSUpgrade(w http.ResponseWriter, r *http.Request) {
+	// Enforce MaxConns limit
+	t.mu.RLock()
+	currentConns := len(t.conns)
+	t.mu.RUnlock()
+
+	if currentConns >= t.config.MaxConns {
+		http.Error(w, "Too many connections", http.StatusServiceUnavailable)
+		return
+	}
+
 	conn, err := t.upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		return
@@ -415,6 +438,13 @@ func (t *Transport) readLoop(pc *PeerConnection) {
 		default:
 		}
 
+		// Set read deadline to prevent blocking forever on unresponsive connections
+		readDeadline := t.config.PingInterval + t.config.PongTimeout
+		if err := pc.Conn.SetReadDeadline(time.Now().Add(readDeadline)); err != nil {
+			log.Printf("[readLoop] SetReadDeadline error for %s: %v", pc.Peer.ID, err)
+			return
+		}
+
 		_, data, err := pc.Conn.ReadMessage()
 		if err != nil {
 			log.Printf("[readLoop] Read error from %s: %v", pc.Peer.ID, err)
@@ -495,6 +525,11 @@ func (pc *PeerConnection) Send(msg *Message) error {
 		return err
 	}
 
+	// Set write deadline to prevent blocking forever
+	if err := pc.Conn.SetWriteDeadline(time.Now().Add(10 * time.Second)); err != nil {
+		return fmt.Errorf("failed to set write deadline: %w", err)
+	}
+
 	return pc.Conn.WriteMessage(websocket.BinaryMessage, data)
 }