diff --git a/src/NimBLECharacteristic.cpp b/src/NimBLECharacteristic.cpp
index 1ffa2bd9..c5c25368 100644
--- a/src/NimBLECharacteristic.cpp
+++ b/src/NimBLECharacteristic.cpp
@@ -28,6 +28,7 @@
 # include "NimBLE2904.h"
 # include "NimBLEDevice.h"
 # include "NimBLELog.h"
+# include "NimBLELocalValueAttribute.h"
 
 static NimBLECharacteristicCallbacks defaultCallback;
 static const char*                   LOG_TAG = "NimBLECharacteristic";
@@ -328,13 +329,17 @@ bool NimBLECharacteristic::sendValue(const uint8_t* value, size_t length, bool i
     return true;
 } // sendValue
 
-void NimBLECharacteristic::readEvent(NimBLEConnInfo& connInfo) {
+void NimBLECharacteristic::readEvent(NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) {
     m_pCallbacks->onRead(this, connInfo);
+    m_pCallbacks->onRead(this, connInfo, args);
 } // readEvent
 
-void NimBLECharacteristic::writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo) {
-    setValue(val, len);
+void NimBLECharacteristic::writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) {
     m_pCallbacks->onWrite(this, connInfo);
+    m_pCallbacks->onWrite(this, connInfo, args);
+    if(!args.isCanceled()) {
+        setValue(val, len);
+    }
 } // writeEvent
 
 /**
@@ -381,9 +386,21 @@ std::string NimBLECharacteristic::toString() const {
  * @param [in] pCharacteristic The characteristic that is the source of the event.
  * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
  */
+void NimBLECharacteristicCallbacks::onRead(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) {
+    NIMBLE_LOGD("NimBLECharacteristicCallbacks", "onRead: default");
+} // onRead
+
 void NimBLECharacteristicCallbacks::onRead(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo) {
     NIMBLE_LOGD("NimBLECharacteristicCallbacks", "onRead: default");
 } // onRead
+/**
+ * @brief Callback function to support a write request.
+ * @param [in] pCharacteristic The characteristic that is the source of the event.
+ * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
+ */
+void NimBLECharacteristicCallbacks::onWrite(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) {
+    NIMBLE_LOGD("NimBLECharacteristicCallbacks", "onWrite: default");
+} // onWrite
 
 /**
  * @brief Callback function to support a write request.
@@ -393,7 +410,6 @@ void NimBLECharacteristicCallbacks::onRead(NimBLECharacteristic* pCharacteristic
 void NimBLECharacteristicCallbacks::onWrite(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo) {
     NIMBLE_LOGD("NimBLECharacteristicCallbacks", "onWrite: default");
 } // onWrite
-
 /**
  * @brief Callback function to support a Notify/Indicate Status report.
  * @param [in] pCharacteristic The characteristic that is the source of the event.
diff --git a/src/NimBLECharacteristic.h b/src/NimBLECharacteristic.h
index 789d21d7..dd2070a7 100644
--- a/src/NimBLECharacteristic.h
+++ b/src/NimBLECharacteristic.h
@@ -28,6 +28,7 @@ class NimBLEDescriptor;
 class NimBLE2904;
 
 # include "NimBLELocalValueAttribute.h"
+# include "NimBLEDevice.h"
 
 # include <string>
 # include <vector>
@@ -226,8 +227,8 @@ class NimBLECharacteristic : public NimBLELocalValueAttribute {
     friend class NimBLEService;
 
     void setService(NimBLEService* pService);
-    void readEvent(NimBLEConnInfo& connInfo) override;
-    void writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo) override;
+    void readEvent(NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) override;
+    void writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) override;
     bool sendValue(const uint8_t* value,
                    size_t         length,
                    bool           is_notification = true,
@@ -249,7 +250,9 @@ class NimBLECharacteristicCallbacks {
   public:
     virtual ~NimBLECharacteristicCallbacks() {}
     virtual void onRead(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo);
+    virtual void onRead(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args);
     virtual void onWrite(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo);
+    virtual void onWrite(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args);
     virtual void onStatus(NimBLECharacteristic* pCharacteristic, int code);
     virtual void onSubscribe(NimBLECharacteristic* pCharacteristic, NimBLEConnInfo& connInfo, uint16_t subValue);
 };
diff --git a/src/NimBLEConnInfo.h b/src/NimBLEConnInfo.h
index cd1e4c3e..767dcfc2 100644
--- a/src/NimBLEConnInfo.h
+++ b/src/NimBLEConnInfo.h
@@ -25,6 +25,7 @@
 #endif
 
 #include "NimBLEAddress.h"
+#include "buffer.h"
 
 /**
  * @brief Connection information.
diff --git a/src/NimBLEDescriptor.cpp b/src/NimBLEDescriptor.cpp
index 8f1bb41e..99fccc60 100644
--- a/src/NimBLEDescriptor.cpp
+++ b/src/NimBLEDescriptor.cpp
@@ -18,6 +18,9 @@
 #include "NimBLEDescriptor.h"
 #if CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_PERIPHERAL)
 
+# include "NimBLELocalAttribute.h"
+# include "NimBLEValueAttribute.h"
+# include "NimBLELocalValueAttribute.h"
 # include "NimBLEService.h"
 # include "NimBLELog.h"
 
@@ -120,13 +123,17 @@ std::string NimBLEDescriptor::toString() const {
     return res;
 } // toString
 
-void NimBLEDescriptor::readEvent(NimBLEConnInfo& connInfo) {
+void NimBLEDescriptor::readEvent(NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) {
     m_pCallbacks->onRead(this, connInfo);
+    m_pCallbacks->onRead(this, connInfo, args);
 } // readEvent
 
-void NimBLEDescriptor::writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo) {
-    setValue(val, len);
+void NimBLEDescriptor::writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) {
     m_pCallbacks->onWrite(this, connInfo);
+    m_pCallbacks->onWrite(this, connInfo, args);
+    if(!args.isCanceled()) {
+        setValue(val, len);
+    }
 } // writeEvent
 
 /**
@@ -134,10 +141,27 @@ void NimBLEDescriptor::writeEvent(const uint8_t* val, uint16_t len, NimBLEConnIn
  * @param [in] pDescriptor The descriptor that is the source of the event.
  * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
  */
-void NimBLEDescriptorCallbacks::onRead(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo) {
+void NimBLEDescriptorCallbacks::onRead(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) {
     NIMBLE_LOGD("NimBLEDescriptorCallbacks", "onRead: default");
 } // onRead
 
+
+/**
+ * @brief Callback function to support a read request.
+ * @param [in] pDescriptor The descriptor that is the source of the event.
+ * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
+ */
+void NimBLEDescriptorCallbacks::onRead(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo) {
+    NIMBLE_LOGD("NimBLEDescriptorCallbacks", "onRead: default");
+} // onRead
+/**
+ * @brief Callback function to support a write request.
+ * @param [in] pDescriptor The descriptor that is the source of the event.
+ * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
+ */
+void NimBLEDescriptorCallbacks::onWrite(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) {
+    NIMBLE_LOGD("NimBLEDescriptorCallbacks", "onWrite: default");
+} // onWrite
 /**
  * @brief Callback function to support a write request.
  * @param [in] pDescriptor The descriptor that is the source of the event.
@@ -147,4 +171,4 @@ void NimBLEDescriptorCallbacks::onWrite(NimBLEDescriptor* pDescriptor, NimBLECon
     NIMBLE_LOGD("NimBLEDescriptorCallbacks", "onWrite: default");
 } // onWrite
 
-#endif // CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_PERIPHERAL)
+#endif // CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_PERIPHERAL)
\ No newline at end of file
diff --git a/src/NimBLEDescriptor.h b/src/NimBLEDescriptor.h
index b6e9b8f2..d4c5d4e4 100644
--- a/src/NimBLEDescriptor.h
+++ b/src/NimBLEDescriptor.h
@@ -21,7 +21,8 @@
 #include "syscfg/syscfg.h"
 #if CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_PERIPHERAL)
 
-# include "NimBLELocalValueAttribute.h"
+#include "NimBLELocalValueAttribute.h"
+# include "NimBLEDevice.h"
 # include <string>
 
 class NimBLECharacteristic;
@@ -49,8 +50,8 @@ class NimBLEDescriptor : public NimBLELocalValueAttribute {
     friend class NimBLEService;
 
     void setCharacteristic(NimBLECharacteristic* pChar);
-    void readEvent(NimBLEConnInfo& connInfo) override;
-    void writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo) override;
+    void readEvent(NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) override;
+    void writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) override;
 
     NimBLEDescriptorCallbacks* m_pCallbacks{nullptr};
     NimBLECharacteristic*      m_pCharacteristic{nullptr};
@@ -67,7 +68,9 @@ class NimBLEDescriptorCallbacks {
   public:
     virtual ~NimBLEDescriptorCallbacks() = default;
     virtual void onRead(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo);
+    virtual void onRead(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args);
     virtual void onWrite(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo);
+    virtual void onWrite(NimBLEDescriptor* pDescriptor, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args);
 };
 
 # include "NimBLE2904.h"
diff --git a/src/NimBLEDevice.h b/src/NimBLEDevice.h
index 37075009..333d20cd 100644
--- a/src/NimBLEDevice.h
+++ b/src/NimBLEDevice.h
@@ -15,9 +15,11 @@
  * limitations under the License.
  */
 
+
 #ifndef NIMBLE_CPP_DEVICE_H_
 #define NIMBLE_CPP_DEVICE_H_
 
+#include "nimconfig.h"
 #include "syscfg/syscfg.h"
 #if CONFIG_BT_NIMBLE_ENABLED
 # ifdef ESP_PLATFORM
@@ -66,11 +68,18 @@ class NimBLEL2CAPServer;
 
 # if MYNEWT_VAL(BLE_ROLE_PERIPHERAL) || MYNEWT_VAL(BLE_ROLE_CENTRAL)
 class NimBLEConnInfo;
+
+class buffer;
+class NimBLEReadEventArgs;
+class NimBLEWriteEventArgs;
+
 # endif
 
+
 class NimBLEAddress;
 class NimBLEDeviceCallbacks;
 
+
 # define BLEDevice                    NimBLEDevice
 # define BLEClient                    NimBLEClient
 # define BLERemoteService             NimBLERemoteService
diff --git a/src/NimBLEEventArgs.h b/src/NimBLEEventArgs.h
new file mode 100644
index 00000000..adb0b5a9
--- /dev/null
+++ b/src/NimBLEEventArgs.h
@@ -0,0 +1,66 @@
+//
+// Created by hoeflich on 30.07.2025.
+//
+
+#ifndef NIMBLEEVENTS_H
+#define NIMBLEEVENTS_H
+
+#if CONFIG_BT_ENABLED && (CONFIG_BT_NIMBLE_ROLE_PERIPHERAL || CONFIG_BT_NIMBLE_ROLE_CENTRAL)
+#include "buffer.h"
+#include <cstring>
+#include <string>
+
+class NimBLEReadEventArgs{
+public:
+    void overwriteReturnValue(const uint8_t* value, int size) {
+        data = new buffer(size);
+        std::memcpy(data->getPointer(), value, size);
+    }
+
+    bool isDataOverwritten() const { return data != nullptr; }
+
+    buffer* getData() { return data; }
+
+    NimBLEReadEventArgs() {}
+
+    ~NimBLEReadEventArgs() {
+        if(data != nullptr)
+            delete data;
+    }
+private:
+    buffer* data = nullptr;
+};
+
+class NimBLEWriteEventArgs{
+public:
+    void Cancel(){
+        canceled = true;
+    }
+
+    bool isCanceled(){
+        return canceled;
+    }
+
+    std::string GetOldData(){
+        return oldData;
+    }
+
+    std::string GetNewData(){
+        return newData;
+    }
+
+    NimBLEWriteEventArgs(std::string oldData, std::string newData) {
+        this->oldData = oldData;
+        this->newData = newData;
+    }
+
+    ~NimBLEWriteEventArgs() {
+    }
+private:
+    std::string oldData;
+    std::string newData;
+    bool canceled = false;
+};
+
+#endif
+#endif //NIMBLEEVENTS_H
diff --git a/src/NimBLEHIDDevice.cpp b/src/NimBLEHIDDevice.cpp
index 105ef11b..fc54745d 100644
--- a/src/NimBLEHIDDevice.cpp
+++ b/src/NimBLEHIDDevice.cpp
@@ -18,6 +18,7 @@
 #include "NimBLEHIDDevice.h"
 #if CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_BROADCASTER) && MYNEWT_VAL(BLE_ROLE_PERIPHERAL)
 
+# include "NimBLEDevice.h"
 # include "NimBLEServer.h"
 # include "NimBLEService.h"
 # include "NimBLE2904.h"
diff --git a/src/NimBLELocalValueAttribute.h b/src/NimBLELocalValueAttribute.h
index 56acb729..536066ab 100644
--- a/src/NimBLELocalValueAttribute.h
+++ b/src/NimBLELocalValueAttribute.h
@@ -51,6 +51,7 @@ typedef enum {
 # include "NimBLEValueAttribute.h"
 # include "NimBLEAttValue.h"
 # include <vector>
+#include "NimBLEEventArgs.h"
 class NimBLEConnInfo;
 
 class NimBLELocalValueAttribute : public NimBLELocalAttribute, public NimBLEValueAttribute {
@@ -113,7 +114,7 @@ class NimBLELocalValueAttribute : public NimBLELocalAttribute, public NimBLEValu
      * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
      * @details This function is called by NimBLEServer when a read request is received.
      */
-    virtual void readEvent(NimBLEConnInfo& connInfo) = 0;
+    virtual void readEvent(NimBLEConnInfo& connInfo, NimBLEReadEventArgs& args) = 0;
 
     /**
      * @brief Callback function to support a write request.
@@ -122,7 +123,7 @@ class NimBLELocalValueAttribute : public NimBLELocalAttribute, public NimBLEValu
      * @param [in] connInfo A reference to a NimBLEConnInfo instance containing the peer info.
      * @details This function is called by NimBLEServer when a write request is received.
      */
-    virtual void writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo) = 0;
+    virtual void writeEvent(const uint8_t* val, uint16_t len, NimBLEConnInfo& connInfo, NimBLEWriteEventArgs& args) = 0;
 
     /**
      * @brief Get a pointer to value of the attribute.
diff --git a/src/NimBLEServer.cpp b/src/NimBLEServer.cpp
index 5e4f381b..bbdc1a7c 100644
--- a/src/NimBLEServer.cpp
+++ b/src/NimBLEServer.cpp
@@ -20,6 +20,7 @@
 
 # include "NimBLEDevice.h"
 # include "NimBLELog.h"
+#include "NimBLEEventArgs.h"
 
 # if MYNEWT_VAL(BLE_ROLE_CENTRAL)
 #  include "NimBLEClient.h"
@@ -631,12 +632,19 @@ int NimBLEServer::handleGattEvent(uint16_t connHandle, uint16_t attrHandle, ble_
         case BLE_GATT_ACCESS_OP_READ_CHR: {
             // Don't call readEvent if the buffer len is 0 (this is a follow up to a previous read),
             // or if this is an internal read (handle is NONE)
+            NimBLEReadEventArgs eventArgs = NimBLEReadEventArgs();
             if (ctxt->om->om_len > 0 && connHandle != BLE_HS_CONN_HANDLE_NONE) {
-                pAtt->readEvent(peerInfo);
+                pAtt->readEvent(peerInfo, eventArgs);
             }
 
             ble_npl_hw_enter_critical();
-            int rc = os_mbuf_append(ctxt->om, val.data(), val.size());
+            int rc;
+            if(eventArgs.isDataOverwritten()) {
+                auto buffer = eventArgs.getData();
+                rc = os_mbuf_append(ctxt->om, buffer->getPointer(), buffer->getSize());
+            } else {
+                rc = os_mbuf_append(ctxt->om, val.data(), val.size());
+            }
             ble_npl_hw_exit_critical(0);
             return rc == 0 ? 0 : BLE_ATT_ERR_INSUFFICIENT_RES;
         }
@@ -652,18 +660,23 @@ int NimBLEServer::handleGattEvent(uint16_t connHandle, uint16_t attrHandle, ble_
             uint8_t buf[maxLen];
             memcpy(buf, ctxt->om->om_data, len);
 
+
             os_mbuf* next;
             next = SLIST_NEXT(ctxt->om, om_next);
             while (next != NULL) {
                 if ((len + next->om_len) > maxLen) {
                     return BLE_ATT_ERR_INVALID_ATTR_VALUE_LEN;
                 }
-                memcpy(&buf[len], next->om_data, next->om_len);
+                    memcpy(&buf[len], next->om_data, next->om_len);
                 len  += next->om_len;
                 next  = SLIST_NEXT(next, om_next);
             }
 
-            pAtt->writeEvent(buf, len, peerInfo);
+            auto oldData = std::string((char*)pAtt->getValue().data(), pAtt->getValue().length());
+            auto newData = std::string((char*)buf, len);
+
+            NimBLEWriteEventArgs eventArgs = NimBLEWriteEventArgs(oldData, newData);
+            pAtt->writeEvent(buf, len, peerInfo, eventArgs);
             return 0;
         }
 
diff --git a/src/NimBLEServer.h b/src/NimBLEServer.h
index 214578ab..94f15c47 100644
--- a/src/NimBLEServer.h
+++ b/src/NimBLEServer.h
@@ -34,6 +34,7 @@
 
 # include <vector>
 # include <array>
+# include "NimBLEEventArgs.h"
 
 # define NIMBLE_ATT_REMOVE_HIDE   1
 # define NIMBLE_ATT_REMOVE_DELETE 2
diff --git a/src/NimBLEService.h b/src/NimBLEService.h
index 11d7c59c..03700eb6 100644
--- a/src/NimBLEService.h
+++ b/src/NimBLEService.h
@@ -23,7 +23,7 @@
 
 class NimBLEService;
 
-# include "NimBLEAttribute.h"
+# include "NimBLEDevice.h"
 # include "NimBLEServer.h"
 # include "NimBLECharacteristic.h"
 
diff --git a/src/buffer.h b/src/buffer.h
new file mode 100644
index 00000000..a8530842
--- /dev/null
+++ b/src/buffer.h
@@ -0,0 +1,46 @@
+//
+// Created by hoeflich on 30.07.2025.
+//
+
+
+
+#ifndef BUFFER_H
+#define BUFFER_H
+
+#if CONFIG_BT_ENABLED && (CONFIG_BT_NIMBLE_ROLE_PERIPHERAL || CONFIG_BT_NIMBLE_ROLE_CENTRAL)
+#include <sys/types.h>
+
+class buffer {
+  public:
+
+  u_int8_t* getPointer() {
+    return data;
+  }
+
+  size_t getSize() {
+    return size;
+  }
+
+  explicit buffer(size_t size){
+    if(size == 0) {
+      this->data = nullptr;
+      this->size = 0;
+      return;
+    }
+
+    this->data = new uint8_t[size];
+    this->size = size;
+  }
+
+  ~buffer(){
+    delete data;
+  }
+
+private:
+  uint8_t *data;
+  size_t size;
+};
+
+#endif
+
+#endif //BUFFER_H