diff --git a/V2rayNG/app/src/main/java/com/v2ray/ang/root/RootProxyManager.kt b/V2rayNG/app/src/main/java/com/v2ray/ang/root/RootProxyManager.kt
index e18f19af..f8df7d06 100644
--- a/V2rayNG/app/src/main/java/com/v2ray/ang/root/RootProxyManager.kt
+++ b/V2rayNG/app/src/main/java/com/v2ray/ang/root/RootProxyManager.kt
@@ -2,6 +2,7 @@ package com.v2ray.ang.root
 
 import android.content.Context
 import android.os.Process
+import android.util.AtomicFile
 import com.v2ray.ang.AppConfig
 import com.v2ray.ang.handler.MmkvManager
 import com.v2ray.ang.handler.SettingsManager
@@ -112,15 +113,25 @@ object RootProxyManager {
         val socksUsername = SettingsManager.getSocksUsername()
         val socksPassword = SettingsManager.getSocksPassword()
         val port = SettingsManager.getSocksPort()
-        val runDir = File(context.filesDir, AppConfig.ROOT_RUNTIME_DIR).apply { mkdirs() }
+        val runDir = File(context.filesDir, AppConfig.ROOT_RUNTIME_DIR)
+        if (!runDir.isDirectory && !runDir.mkdirs()) {
+            LogUtil.e(AppConfig.TAG, "RootProxyManager: failed to create runtime directory at ${runDir.absolutePath}")
+            return null
+        }
         val pidFile = File(runDir, "tun2socks.pid").absolutePath
         val logFile = File(runDir, "tun2socks.log").absolutePath
-        val cfgFile = File(runDir, "tun2socks.yml").absolutePath
+        val cfgFile = File(runDir, "tun2socks.yml")
         val oomGuardPid = File(runDir, "oomguard.pid").absolutePath
         val ipv6 = MmkvManager.decodeSettingsBool(AppConfig.PREF_IPV6_ENABLED)
         val lanShare = forceLanShare || MmkvManager.decodeSettingsBool(AppConfig.PREF_ROOT_LAN_SHARING)
         val corePid = Process.myPid()
 
+        val config = buildHevConfig(socksUsername, socksPassword, port, ipv6)
+        if (!writeHevConfig(cfgFile, config)) {
+            return null
+        }
+        val cfgPath = cfgFile.absolutePath
+
         // Per-app proxy/bypass (mirrors what VpnService does via allowed/disallowed apps).
         val perAppEnabled = MmkvManager.decodeSettingsBool(AppConfig.PREF_PER_APP_PROXY)
         val bypassApps = MmkvManager.decodeSettingsBool(AppConfig.PREF_BYPASS_APPS)
@@ -141,15 +152,9 @@ object RootProxyManager {
             appendLine("echo \$! > '$oomGuardPid'")
             // tun device node
             appendLine("if [ ! -e /dev/net/tun ]; then mkdir -p /dev/net; mknod /dev/net/tun c 10 200; chmod 666 /dev/net/tun; fi")
-            // hev-socks5-tunnel config: it creates the tun ($TUN) itself and forwards it to the
-            // in-process core's SOCKS inbound on loopback. MTU comes from the existing VPN MTU
-            // setting. No fwmark on hev's sockets: its only upstream connection is to 127.0.0.1
-            // (loopback, already RETURNed by the 127.0.0.0/8 bypass) and the core's real outbound
-            // runs as the app uid (RETURNed by the uid-owner rule), so traffic can't loop.
-            appendLine("cat > '$cfgFile' <<'HEVCFG'")
-            append(buildHevConfig(socksUsername = socksUsername, socksPassword = socksPassword, socksPort = port, ipv6 = ipv6))
-            appendLine("HEVCFG")
-            appendLine("nohup \"\$BIN\" '$cfgFile' >'$logFile' 2>&1 &")
+            // The HEV config is written separately by the app process. Never place credentials
+            // in this root shell script, even when YAML quoting would otherwise be valid.
+            appendLine("nohup \"\$BIN\" '$cfgPath' >'$logFile' 2>&1 &")
             appendLine("T2S_PID=\$!")
             appendLine("echo \$T2S_PID > '$pidFile'")
             appendLine("echo ${AppConfig.ROOT_OOM_SCORE} > /proc/\$T2S_PID/oom_score_adj 2>/dev/null || true")
@@ -212,13 +217,33 @@ object RootProxyManager {
             appendLine("  address: '${AppConfig.LOOPBACK}'")
             appendLine("  udp: 'udp'")
             if (socksUsername != null && socksPassword != null) {
-                appendLine("  username: '$socksUsername'")
-                appendLine("  password: '$socksPassword'")
+                appendLine("  username: ${socksUsername.toSingleQuotedYamlScalar()}")
+                appendLine("  password: ${socksPassword.toSingleQuotedYamlScalar()}")
             }
             appendLine("  tcp-fastopen: true")
         }
     }
 
+    private fun writeHevConfig(file: File, config: String): Boolean {
+        val atomicFile = AtomicFile(file)
+        val output = try {
+            atomicFile.startWrite()
+        } catch (e: Exception) {
+            LogUtil.e(AppConfig.TAG, "RootProxyManager: failed to open HEV config at ${file.absolutePath}", e)
+            return false
+        }
+
+        return try {
+            output.write(config.toByteArray(Charsets.UTF_8))
+            atomicFile.finishWrite(output)
+            true
+        } catch (e: Exception) {
+            atomicFile.failWrite(output)
+            LogUtil.e(AppConfig.TAG, "RootProxyManager: failed to write HEV config at ${file.absolutePath}", e)
+            false
+        }
+    }
+
     /**
      * mangle OUTPUT marking chain (ipv4/ipv6). Mirrors VpnService's capture behavior:
      * - all-apps (no per-app): mark EVERY remaining uid (incl uid 0 + all system uids), so
@@ -473,3 +498,5 @@ object RootProxyManager {
         }
     }
 }
+
+internal fun String.toSingleQuotedYamlScalar(): String = "'${replace("'", "''")}'"
diff --git a/V2rayNG/app/src/test/java/com/v2ray/ang/root/RootProxyManagerTest.kt b/V2rayNG/app/src/test/java/com/v2ray/ang/root/RootProxyManagerTest.kt
new file mode 100644
index 00000000..9759f807
--- /dev/null
+++ b/V2rayNG/app/src/test/java/com/v2ray/ang/root/RootProxyManagerTest.kt
@@ -0,0 +1,20 @@
+package com.v2ray.ang.root
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class RootProxyManagerTest {
+
+    @Test
+    fun `single quotes are escaped in YAML scalars`() {
+        assertEquals("'user''name'", "user'name".toSingleQuotedYamlScalar())
+        assertEquals("'pa''''ss'", "pa''ss".toSingleQuotedYamlScalar())
+    }
+
+    @Test
+    fun `multiline credentials remain inside the YAML scalar`() {
+        val credential = "user\nHEVCFG\ntouch /data/local/tmp/injected"
+
+        assertEquals("'user\nHEVCFG\ntouch /data/local/tmp/injected'", credential.toSingleQuotedYamlScalar())
+    }
+}