diff --git a/server/db/mysql/tenant_adapter.go b/server/db/mysql/tenant_adapter.go
index 8cf1ced..6a5492f 100644
--- a/server/db/mysql/tenant_adapter.go
+++ b/server/db/mysql/tenant_adapter.go
@@ -7201,6 +7201,10 @@ func (a *adapter) TenantUserSearch(id t.TenantID, viewer t.Uid, queryText, searc
 	}
 	where := []string{"u.id<>?", "u.state=?"}
 	args := []any{decodeUID(viewer), t.StateOK}
+	if !a.tenantScopedDB {
+		where = append([]string{"u.tenant_id=?"}, where...)
+		args = append([]any{id}, args...)
+	}
 	if cursor != "" {
 		parsed, err := strconv.ParseInt(cursor, 10, 64)
 		if err != nil || parsed <= 0 {
@@ -7213,6 +7217,12 @@ func (a *adapter) TenantUserSearch(id t.TenantID, viewer t.Uid, queryText, searc
 		"LEFT JOIN im_user_privacy_settings AS privacy ON privacy.user_id=u.id",
 		"LEFT JOIN im_user_profiles AS profile ON profile.user_id=u.id",
 	}
+	if !a.tenantScopedDB {
+		joins = []string{
+			"LEFT JOIN im_user_privacy_settings AS privacy ON privacy.tenant_id=u.tenant_id AND privacy.user_id=u.id",
+			"LEFT JOIN im_user_profiles AS profile ON profile.tenant_id=u.tenant_id AND profile.user_id=u.id",
+		}
+	}
 	addMethod := "account"
 	switch searchType {
 	case "", "account":
diff --git a/server/db/mysql/tests/mysql_test.go b/server/db/mysql/tests/mysql_test.go
index 96e3e9f..2aa40b1 100644
--- a/server/db/mysql/tests/mysql_test.go
+++ b/server/db/mysql/tests/mysql_test.go
@@ -407,6 +407,69 @@ func TestTenantUserSearchMatchesUsernamePhoneAndPublicAccount(t *testing.T) {
 	}
 }
 
+func TestTenantUserSearchDoesNotLeakAcrossTenants(t *testing.T) {
+	businessAdp, ok := adp.(adapter.TenantBusinessAdapter)
+	if !ok {
+		t.Fatal("MySQL adapter does not implement TenantBusinessAdapter")
+	}
+	var tenantColumns int
+	if err := db.Get(&tenantColumns, `SELECT COUNT(*) FROM information_schema.columns
+		WHERE table_schema=DATABASE() AND table_name='im_users' AND column_name='tenant_id'`); err != nil {
+		t.Fatal(err)
+	}
+	if tenantColumns == 0 {
+		t.Skip("im_users.tenant_id is missing in the current test database")
+	}
+	var tenantID types.TenantID
+	if err := db.Get(&tenantID, "SELECT id FROM im_tenant WHERE code='default'"); err != nil {
+		t.Fatal(err)
+	}
+
+	now := types.TimeNow()
+	viewerID := now.UnixNano() & 0x3fffffffffffffff
+	targetID := viewerID + 1
+	otherTenantID := tenantID + 1000
+	otherTargetID := targetID + 1000
+	viewer := store.EncodeUid(viewerID)
+	target := store.EncodeUid(targetID)
+	t.Cleanup(func() {
+		db.Exec("DELETE FROM im_user_privacy_settings WHERE user_id IN (?,?,?)", viewerID, targetID, otherTargetID)
+		db.Exec("DELETE FROM im_user_profiles WHERE user_id IN (?,?,?)", viewerID, targetID, otherTargetID)
+		db.Exec("DELETE FROM im_users WHERE id IN (?,?,?)", viewerID, targetID, otherTargetID)
+	})
+
+	for _, row := range []struct {
+		tenantID types.TenantID
+		userID   int64
+		username string
+	}{
+		{tenantID, viewerID, "viewer-scope"},
+		{tenantID, targetID, "shared-name"},
+		{otherTenantID, otherTargetID, "shared-name"},
+	} {
+		if _, err := db.Exec(
+			`INSERT INTO im_users(tenant_id,id,account_no,username,createdat,updatedat,state,access,phone,trusted)
+			 VALUES(?,?,?,?,?,?,?,?,?,?)`,
+			row.tenantID, row.userID, row.userID%1000000, row.username, now, now, types.StateOK, `{"Auth":"JRWPAS","Anon":"N"}`, nil, `{}`); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := db.Exec(
+			`INSERT INTO im_user_privacy_settings(tenant_id,id,user_id,add_me_methods,created_at,updated_at)
+			 VALUES(?,?,?,?,?,?)`,
+			row.tenantID, row.userID+1000, row.userID, `{"account":true,"phone":true,"qr":true,"group":true}`, now, now); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	users, _, err := businessAdp.TenantUserSearch(tenantID, viewer, "shared-name", "account", "", 20)
+	if err != nil {
+		t.Fatalf("tenant-scoped search failed: %v", err)
+	}
+	if len(users) != 1 || users[0].Uid() != target {
+		t.Fatalf("tenant-scoped search returned %+v, want %s only", users, target.UserId())
+	}
+}
+
 // ================== Create tests ================================
 func TestUserCreate(t *testing.T) {
 	for _, user := range testData.Users {