diff --git a/App/app/aircopy.c b/App/app/aircopy.c
index b9790346..e0a4e356 100644
--- a/App/app/aircopy.c
+++ b/App/app/aircopy.c
@@ -88,13 +88,14 @@ DECLARE_AIRCOPY_BANK(1)
 // For settings only
 
 static const AIRCOPY_Segment_t AIRCOPY_Segments_Settings[] = {
-    { 0xA000, 0xA170, AIRCOPY_WRITE_BYTES },
-    { 0x880E, 0x886E, AIRCOPY_WRITE_BYTES },
-    { 0x9000, 0x90E5, AIRCOPY_WRITE_BYTES }, // VFO area (full 14 VFOs 0x9000..0x90E0) +
-                                             // Fox Hunt settings tail 0x90E0..0x90E5
+    // Ends are rounded to full Aircopy blocks. The extra bytes are unmapped
+    // EEPROM-compat holes (0x90E0..0x90E6 is the complete Fox Hunt tail).
+    { 0xA000, 0xA180, AIRCOPY_WRITE_BYTES },
+    { 0x880E, 0x888E, AIRCOPY_WRITE_BYTES },
+    { 0x9000, 0x9100, AIRCOPY_WRITE_BYTES },
 };
 
-// total_blocks = ceil(0x170/64) + ceil(0x60/64) + ceil(0xE5/64) = 6 + 2 + 4 = 12
+// total_blocks = 0x180/64 + 0x80/64 + 0x100/64 = 6 + 2 + 4 = 12
 static const AIRCOPY_TransferMap_t AIRCOPY_Map_Settings = {
     .segments = AIRCOPY_Segments_Settings,
     .num_segments = 3,
@@ -154,7 +155,8 @@ static inline const AIRCOPY_Segment_t *AIRCOPY_FindSegmentForOffset(uint16_t off
     {
         const AIRCOPY_Segment_t *seg = &map->segments[i];
 
-        if (off >= seg->start_offset && off < seg->end_offset)
+        if (off >= seg->start_offset && off < seg->end_offset &&
+            ((off - seg->start_offset) & (AIRCOPY_BLOCK_SIZE - 1u)) == 0u)
             return seg;
     }
 
@@ -426,4 +428,4 @@ void AIRCOPY_ProcessKeys(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
     gRequestDisplayScreen = DISPLAY_AIRCOPY;
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/App/app/beam.c b/App/app/beam.c
index 0f024757..fab2923d 100644
--- a/App/app/beam.c
+++ b/App/app/beam.c
@@ -174,7 +174,6 @@ static void BEAM_SavePayloadToFirstFreeChannel(const BEAM_Payload_t *payload)
     VFO_Info_t vfo;
     RADIO_InitInfo(&vfo, channel, payload->rx_frequency);
 
-    // CRC + magic + version already validate the payload — no need to clamp fields.
     vfo.TX_OFFSET_FREQUENCY = payload->tx_offset_frequency;
     vfo.freq_config_RX.Code = payload->rx_code;
     vfo.freq_config_TX.Code = payload->tx_code;
@@ -191,10 +190,9 @@ static void BEAM_SavePayloadToFirstFreeChannel(const BEAM_Payload_t *payload)
 #ifdef ENABLE_DTMF_CALLING
     vfo.DTMF_DECODING_ENABLE = payload->dtmf_decoding_enable;
 #endif
-    vfo.STEP_SETTING = payload->step_setting;
+    vfo.STEP_SETTING = payload->step_setting < STEP_N_ELEM ? payload->step_setting : STEP_12_5kHz;
     vfo.StepFrequency = gStepFrequencyTable[vfo.STEP_SETTING];
     vfo.SCRAMBLING_TYPE = payload->scrambling_type;
-    vfo.Band = payload->band;
     vfo.SCANLIST_PARTICIPATION = payload->scanlist;
     vfo.Compander = payload->compander;
     
diff --git a/App/app/uart.c b/App/app/uart.c
index 54eb91b0..a298cefb 100644
--- a/App/app/uart.c
+++ b/App/app/uart.c
@@ -298,9 +298,10 @@ static void SendVersion(uint32_t Port)
 {
     REPLY_0514_t Reply;
 
+    Reply.Data.Padding[0] = Reply.Data.Padding[1] = 0;
     Reply.Header.ID = 0x0515;
     Reply.Header.Size = sizeof(Reply.Data);
-    strcpy(Reply.Data.Version, Version);
+    strncpy(Reply.Data.Version, Version, sizeof(Reply.Data.Version));
     Reply.Data.bHasCustomAesKey = bHasCustomAesKey;
     Reply.Data.bIsInLockScreen = bIsInLockScreen;
     Reply.Data.Challenge[0] = gChallenge[0];
@@ -434,6 +435,9 @@ static void CMD_051D(uint32_t Port, const uint8_t *pBuffer)
 
     uint32_t Timestamp = 0;
 
+    if ((pCmd->Size & 7u) || pCmd->Header.Size < 8u + pCmd->Size)
+        return;
+
     if(0) {}
 #if defined(ENABLE_UART)
     else if (Port == UART_PORT_UART)
@@ -560,6 +564,7 @@ static void CMD_052D(uint32_t Port, const uint8_t *pBuffer)
     
     gIsLocked            = bIsLocked;
     Reply.Data.bIsLocked = bIsLocked;
+    Reply.Data.Padding[0] = Reply.Data.Padding[1] = Reply.Data.Padding[2] = 0;
 
     SendReply(Port, &Reply, sizeof(Reply));
 }
@@ -796,7 +801,9 @@ bool UART_IsCommandAvailable(uint32_t Port)
 
     Crc = pUART_Command->Buffer[Size] | (pUART_Command->Buffer[Size + 1] << 8);
 
-    return CRC_Calculate(pUART_Command->Buffer, Size) == Crc;
+    return Size >= sizeof(Header_t) &&
+           pUART_Command->Header.Size <= Size - sizeof(Header_t) &&
+           CRC_Calculate(pUART_Command->Buffer, Size) == Crc;
 }
 
 #ifdef ENABLE_FEAT_F4HWN_MULTIBOOT
@@ -936,6 +943,8 @@ void UART_HandleCommand(uint32_t Port)
 
         case 0x0724: // slot write: program bytes at slot+offset (slot pre-erased)
         {
+            if (pUART_Command->Header.Size < 12u)
+                break;
             gSerialConfigCountDown_500ms = 12; // keep serial mode alive (6 s)
             uint8_t  slot   = pUART_Command->Data[0];
             uint32_t offset = (uint32_t)pUART_Command->Data[2]
@@ -951,7 +960,7 @@ void UART_HandleCommand(uint32_t Port)
             uint8_t status;
             if (ts != mb_port_timestamp(Port))
                 status = MB_ERR_AUTH;
-            else if (len > 240u)  // 12-byte prefix + data must fit Data[252]
+            else if (len > pUART_Command->Header.Size - 12u)
                 status = MB_ERR_SIZE;
             else
                 status = MB_SlotWrite(slot, offset, &pUART_Command->Data[12], len);
diff --git a/App/ui/welcome.c b/App/ui/welcome.c
index 659079e7..37e288a8 100644
--- a/App/ui/welcome.c
+++ b/App/ui/welcome.c
@@ -255,15 +255,17 @@ void UI_DisplayWelcome(void)
     }
 #endif
     else {
-        char WelcomeString0[16];
-        char WelcomeString1[16];
+        char WelcomeString0[17];
+        char WelcomeString1[17];
         char WelcomeString2[16];
         char WelcomeString3[32];
 
         // 0x0EB0
         PY25Q16_ReadBuffer(0x00A0C8, WelcomeString0, 16);
+        WelcomeString0[16] = '\0';
         // 0x0EC0
         PY25Q16_ReadBuffer(0x00A0D8, WelcomeString1, 16);
+        WelcomeString1[16] = '\0';
 
         sprintf(WelcomeString2, "%u.%02uV %u%%",
                 gBatteryVoltageAverage / 100,