diff --git a/pkg/util/xlog/xlog.go b/pkg/util/xlog/xlog.go
index 1021d44a..6627dc2a 100644
--- a/pkg/util/xlog/xlog.go
+++ b/pkg/util/xlog/xlog.go
@@ -17,6 +17,8 @@ package xlog
 import (
 	"cmp"
 	"slices"
+	"sync"
+	"sync/atomic"
 
 	"github.com/fatedier/frp/pkg/util/log"
 )
@@ -30,11 +32,13 @@ type LogPrefix struct {
 	Priority int
 }
 
-// Logger is not thread safety for operations on prefix
+// Logger supports concurrent logging and prefix updates.
+// A Logger must not be copied after first use.
 type Logger struct {
+	mu       sync.Mutex
 	prefixes []LogPrefix
 
-	prefixString string
+	prefixString atomic.Pointer[string]
 }
 
 func New() *Logger {
@@ -44,9 +48,11 @@ func New() *Logger {
 }
 
 func (l *Logger) ResetPrefixes() (old []LogPrefix) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
 	old = l.prefixes
 	l.prefixes = make([]LogPrefix, 0)
-	l.prefixString = ""
+	l.prefixString.Store(nil)
 	return
 }
 
@@ -59,6 +65,8 @@ func (l *Logger) AppendPrefix(prefix string) *Logger {
 }
 
 func (l *Logger) AddPrefix(prefix LogPrefix) *Logger {
+	l.mu.Lock()
+	defer l.mu.Unlock()
 	found := false
 	if prefix.Priority <= 0 {
 		prefix.Priority = 10
@@ -78,39 +86,50 @@ func (l *Logger) AddPrefix(prefix LogPrefix) *Logger {
 	return l
 }
 
+// The caller must hold l.mu or exclusively own an unpublished logger.
 func (l *Logger) renderPrefixString() {
 	slices.SortStableFunc(l.prefixes, func(a, b LogPrefix) int {
 		return cmp.Compare(a.Priority, b.Priority)
 	})
-	l.prefixString = ""
+	var prefixString string
 	for _, v := range l.prefixes {
-		l.prefixString += "[" + v.Value + "] "
+		prefixString += "[" + v.Value + "] "
 	}
+	l.prefixString.Store(&prefixString)
 }
 
 func (l *Logger) Spawn() *Logger {
 	nl := New()
+	l.mu.Lock()
 	nl.prefixes = append(nl.prefixes, l.prefixes...)
+	l.mu.Unlock()
 	nl.renderPrefixString()
 	return nl
 }
 
+func (l *Logger) getPrefixString() string {
+	if prefix := l.prefixString.Load(); prefix != nil {
+		return *prefix
+	}
+	return ""
+}
+
 func (l *Logger) Errorf(format string, v ...any) {
-	log.Logger.WithPrefix(l.prefixString).Errorf(format, v...)
+	log.Logger.WithPrefix(l.getPrefixString()).Errorf(format, v...)
 }
 
 func (l *Logger) Warnf(format string, v ...any) {
-	log.Logger.WithPrefix(l.prefixString).Warnf(format, v...)
+	log.Logger.WithPrefix(l.getPrefixString()).Warnf(format, v...)
 }
 
 func (l *Logger) Infof(format string, v ...any) {
-	log.Logger.WithPrefix(l.prefixString).Infof(format, v...)
+	log.Logger.WithPrefix(l.getPrefixString()).Infof(format, v...)
 }
 
 func (l *Logger) Debugf(format string, v ...any) {
-	log.Logger.WithPrefix(l.prefixString).Debugf(format, v...)
+	log.Logger.WithPrefix(l.getPrefixString()).Debugf(format, v...)
 }
 
 func (l *Logger) Tracef(format string, v ...any) {
-	log.Logger.WithPrefix(l.prefixString).Tracef(format, v...)
+	log.Logger.WithPrefix(l.getPrefixString()).Tracef(format, v...)
 }
diff --git a/pkg/util/xlog/xlog_concurrency_test.go b/pkg/util/xlog/xlog_concurrency_test.go
new file mode 100644
index 00000000..b8d90670
--- /dev/null
+++ b/pkg/util/xlog/xlog_concurrency_test.go
@@ -0,0 +1,47 @@
+// Copyright 2026 The frp Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package xlog
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestLoggerConcurrentPrefixAccess(t *testing.T) {
+	captureLogs(t)
+	xl := New().AddPrefix(LogPrefix{Name: "runID", Value: "old-run"})
+	start := make(chan struct{})
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		<-start
+		xl.AddPrefix(LogPrefix{Name: "runID", Value: "new-run"})
+		xl.AppendPrefix("proxy")
+		xl.ResetPrefixes()
+	}()
+	go func() {
+		defer wg.Done()
+		<-start
+		xl.Spawn().Tracef("spawn")
+		xl.Errorf("error")
+		xl.Warnf("warn")
+		xl.Infof("info")
+		xl.Debugf("debug")
+		xl.Tracef("trace")
+	}()
+	close(start)
+	wg.Wait()
+}