diff --git a/easebuzz/api.py b/easebuzz/api.py
index 30c012a..67b6823 100644
--- a/easebuzz/api.py
+++ b/easebuzz/api.py
@@ -1,16 +1,19 @@
 import frappe
 import requests
 
+
 @frappe.whitelist(allow_guest=True)
 def webhook_handler(**kwargs):
     try:
         data = frappe.parse_json(kwargs)
         controller = frappe.get_last_doc("Easebuzz Settings")
         if data.get("udf3") == "webform":
-            controller.handle_response_web_form(data)
-        else:
-            controller.handle_response(data)
-            url = "https://fees.walnutedu.in/index.php/payment/easebuzz_webhook_callback"
-            r = requests.post(url, json = data)
+            return controller.handle_response_web_form(data)
+        controller.handle_response(data)
+        url = "https://fees.walnutedu.in/index.php/payment/easebuzz_webhook_callback"
+        requests.post(url, json=data, timeout=(5, 30))
+        return {"message": "ok"}
     except Exception as e:
-        frappe.logger("easebuzz").exception(e)
\ No newline at end of file
+        frappe.local.response["http_status_code"] = 400
+        frappe.logger("easebuzz").exception(e)
+        return {"message": "invalid callback"}
diff --git a/easebuzz/easebuzz/doctype/easebuzz_settings/easebuzz_settings.py b/easebuzz/easebuzz/doctype/easebuzz_settings/easebuzz_settings.py
index 59d133b..782593c 100644
--- a/easebuzz/easebuzz/doctype/easebuzz_settings/easebuzz_settings.py
+++ b/easebuzz/easebuzz/doctype/easebuzz_settings/easebuzz_settings.py
@@ -2,8 +2,11 @@
 # For license information, please see license.txt
 
 import json
+
 import frappe
+from frappe import _
 from frappe.model.document import Document
+from easebuzz.easebuzz.utils import payment as easebuzz_payment
 from easebuzz.easebuzz.utils.easebuzz_payment_gateway import Easebuzz
 from frappe.utils import call_hook_method
 from frappe.utils.data import cint, flt
@@ -169,19 +172,36 @@ def get_settings(self, data):
 
         return settings
 
+    def validate_gateway_response(self, data):
+        salt = self.get_password(fieldname="salt", raise_exception=False)
+        response = easebuzz_payment.easebuzzResponse(data, salt)
+        if response.get("status") != 1:
+            frappe.throw(_("Invalid Easebuzz callback"))
+        return response.get("data", {})
+
+    def _reject_replay(self, doc, transaction_id):
+        existing_transaction_id = getattr(doc, "transaction_id", None)
+        if existing_transaction_id and existing_transaction_id != transaction_id:
+            frappe.throw(_("Conflicting transaction callback received"))
+        if existing_transaction_id == transaction_id:
+            return True
+        return False
+
     def handle_response(self, data):
+        data = self.validate_gateway_response(data)
         payment_request_doctype = data.get("udf1")
         payment_request_docname = data.get("udf2")
         status = data.get("status")
         transaction_id = data.get("txnid")
         if status == "success":
             if frappe.db.exists(payment_request_doctype, payment_request_docname):
-                frappe.msgprint("Payment Request exists")
                 payment_request = frappe.get_doc(
                     payment_request_doctype,
                     payment_request_docname,
                     ignore_permissions=True,
                 )
+                if self._reject_replay(payment_request, transaction_id):
+                    return {"message": "Duplicate callback ignored"}
                 frappe.db.set_value(
                     payment_request_doctype,
                     payment_request_docname,
@@ -190,10 +210,10 @@ def handle_response(self, data):
                 )
                 payment_request.on_payment_authorized(status="Completed")
                 return {"message": "Payment Successful"}
-            else:
-                frappe.msgprint("Payment Request does not exist, Invalid Request")
+            frappe.throw(_("Payment Request does not exist, Invalid Request"))
 
     def handle_response_web_form(self, data):
+        data = self.validate_gateway_response(data)
         doctype = data.get("udf1")
         docname = data.get("udf2")
         docname = docname.replace("@", "(").replace("#", ")")
@@ -201,11 +221,12 @@ def handle_response_web_form(self, data):
         transaction_id = data.get("txnid")
         if status == "success":
             if frappe.db.exists(doctype, docname):
-                frappe.db.set_value(doctype, docname, "transaction_id", transaction_id)
                 doc = frappe.get_doc(doctype, docname, ignore_permissions=True)
+                if self._reject_replay(doc, transaction_id):
+                    return {"message": "Duplicate callback ignored"}
+                frappe.db.set_value(doctype, docname, "transaction_id", transaction_id)
                 return doc.validate_payment(data)
-            else:
-                frappe.log_error(f"{doctype} {docname} does not exist")
+            frappe.throw(_("{0} {1} does not exist").format(doctype, docname))
 
     def initiateRefund(self, data):
         amounts = float(data.get("amount"))
@@ -223,8 +244,10 @@ def initiateRefund(self, data):
         return response
 
 
-@frappe.whitelist(allow_guest=True)
+@frappe.whitelist()
 def get_merchant_key():
+    if frappe.session.user == "Guest":
+        frappe.throw(_("Authentication required"), frappe.PermissionError)
     controller = frappe.get_doc("Easebuzz Settings")
     return controller.merchant_key
 
diff --git a/easebuzz/easebuzz/utils/http.py b/easebuzz/easebuzz/utils/http.py
new file mode 100644
index 0000000..7466793
--- /dev/null
+++ b/easebuzz/easebuzz/utils/http.py
@@ -0,0 +1,34 @@
+import time
+
+import requests
+from requests import RequestException
+
+DEFAULT_CONNECT_TIMEOUT = 5
+DEFAULT_READ_TIMEOUT = 30
+DEFAULT_MAX_ATTEMPTS = 3
+DEFAULT_BACKOFF_SECONDS = 1
+DEFAULT_STATUS_RETRY_CODES = {408, 429, 500, 502, 503, 504}
+
+
+def post_with_retries(url, data, timeout=None, max_attempts=DEFAULT_MAX_ATTEMPTS, backoff_seconds=DEFAULT_BACKOFF_SECONDS, retry_status_codes=None):
+    timeout = timeout or (DEFAULT_CONNECT_TIMEOUT, DEFAULT_READ_TIMEOUT)
+    retry_status_codes = retry_status_codes or DEFAULT_STATUS_RETRY_CODES
+    last_error = None
+
+    for attempt in range(1, max_attempts + 1):
+        try:
+            response = requests.post(url, data, timeout=timeout)
+            if response.status_code not in retry_status_codes or attempt == max_attempts:
+                return response
+            last_error = requests.HTTPError(f"Retryable HTTP status: {response.status_code}", response=response)
+        except (requests.Timeout, requests.ConnectionError) as exc:
+            last_error = exc
+            if attempt == max_attempts:
+                raise
+        except RequestException:
+            raise
+
+        time.sleep(backoff_seconds * (2 ** (attempt - 1)))
+
+    if last_error:
+        raise last_error
diff --git a/easebuzz/easebuzz/utils/payment.py b/easebuzz/easebuzz/utils/payment.py
index 95b59ac..e8370af 100644
--- a/easebuzz/easebuzz/utils/payment.py
+++ b/easebuzz/easebuzz/utils/payment.py
@@ -1,10 +1,11 @@
 from hashlib import sha512
 
-import requests
 import json
 import re
 import traceback
 
+from .http import post_with_retries
+
 # import webbrowser
 
 '''
@@ -538,7 +539,7 @@ def _pay(params_array, salt_key, url):
     params_array['hash'] = hash_key
 
     # requests call for initiate pay link
-    request_result = requests.post(url + 'payment/initiateLink', params_array)
+    request_result = post_with_retries(url + 'payment/initiateLink', params_array)
     result = json.loads(request_result.content)
     # print(params_array)
     if result['status'] == 1:
diff --git a/easebuzz/easebuzz/utils/payout.py b/easebuzz/easebuzz/utils/payout.py
index 73721a4..e7132a5 100644
--- a/easebuzz/easebuzz/utils/payout.py
+++ b/easebuzz/easebuzz/utils/payout.py
@@ -1,10 +1,11 @@
 from hashlib import sha512
 
-import requests
 import json
 import re
 import traceback
 
+from .http import post_with_retries
+
 '''
 *
 * get_payout_details_by_date method payout amount and dispay the payout response.
@@ -342,7 +343,7 @@ def _payoutPayment(params_array, salt_key, url):
     params_array['hash'] = hash_key
 
     # requests call for retrive all payout
-    request_result = requests.post(url + 'payout/v1/retrieve', params_array)
+    request_result = post_with_retries(url + 'payout/v1/retrieve', params_array)
     result = json.loads(request_result.content)
 
     return result
diff --git a/easebuzz/easebuzz/utils/refund.py b/easebuzz/easebuzz/utils/refund.py
index 8ede35a..a9126df 100644
--- a/easebuzz/easebuzz/utils/refund.py
+++ b/easebuzz/easebuzz/utils/refund.py
@@ -1,10 +1,11 @@
 from hashlib import sha512
 
-import requests
 import json
 import re
 import traceback
 
+from .http import post_with_retries
+
 '''
 *
 * initiate_refund method refund amount and call dispay the refund page.
@@ -387,7 +388,7 @@ def _refundPayment(params_array, salt_key, url):
     params_array['hash'] = hash_key
 
     # requests call for retrive transaction
-    request_result = requests.post(url + 'transaction/v1/refund', params_array)
+    request_result = post_with_retries(url + 'transaction/v1/refund', params_array)
 
     return json.loads(request_result.content)
 
diff --git a/easebuzz/easebuzz/utils/transaction.py b/easebuzz/easebuzz/utils/transaction.py
index 4c02362..ab9b409 100644
--- a/easebuzz/easebuzz/utils/transaction.py
+++ b/easebuzz/easebuzz/utils/transaction.py
@@ -1,10 +1,11 @@
 from hashlib import sha512
 
-import requests
 import json
 import re
 import traceback
 
+from .http import post_with_retries
+
 '''
 *
 * get_transaction_details method use for transaction
@@ -376,7 +377,7 @@ def _getTransaction(params_array, salt_key, url):
     params_array['hash'] = hash_key
 
     # requests call for retrive transaction
-    request_result = requests.post(url + 'transaction/v1/retrieve', params_array)
+    request_result = post_with_retries(url + 'transaction/v1/retrieve', params_array)
 
     return json.loads(request_result.content)
 
diff --git a/easebuzz/easebuzz/utils/transaction_date.py b/easebuzz/easebuzz/utils/transaction_date.py
index a95767b..16fc419 100644
--- a/easebuzz/easebuzz/utils/transaction_date.py
+++ b/easebuzz/easebuzz/utils/transaction_date.py
@@ -1,10 +1,11 @@
 from hashlib import sha512
 
-import requests
 import json
 import re
 import traceback
 
+from .http import post_with_retries
+
 '''
 *
 * get_transactions_by_date method use for transaction based on date
@@ -296,7 +297,7 @@ def _getDateTransaction(params_array, salt_key, url):
     params_array['hash'] = hash_key
 
     # requests call for retrive transaction based on date
-    request_result = requests.post(url + 'transaction/v1/retrieve/date', params_array)
+    request_result = post_with_retries(url + 'transaction/v1/retrieve/date', params_array)
     temp_result = json.loads(request_result.content)
 
     return temp_result
diff --git a/easebuzz/www/easebuzz/success.py b/easebuzz/www/easebuzz/success.py
index 5e766b1..df476dc 100644
--- a/easebuzz/www/easebuzz/success.py
+++ b/easebuzz/www/easebuzz/success.py
@@ -3,14 +3,9 @@
 
 def get_context(context):
     try:
-        if frappe.session.user == "Guest":
-            frappe.set_user("Administrator")
-            data = frappe.form_dict
-            handle_data(data)
-            frappe.set_user("Guest")
-        else:
-            handle_data(data)
+        handle_data(frappe.form_dict)
     except Exception as e:
+        frappe.local.response["http_status_code"] = 400
         frappe.logger("easebuzz").exception(e)
 
 
diff --git a/tests_security_smoke.py b/tests_security_smoke.py
new file mode 100644
index 0000000..9ce2496
--- /dev/null
+++ b/tests_security_smoke.py
@@ -0,0 +1,47 @@
+from hashlib import sha512
+from unittest.mock import patch
+
+import requests
+
+from easebuzz.easebuzz.utils import payment
+from easebuzz.easebuzz.utils.http import post_with_retries
+
+
+def build_callback_payload(salt="secret"):
+    data = {
+        "status": "success",
+        "txnid": "txn-1",
+        "amount": "100.00",
+        "productinfo": "Order",
+        "firstname": "Test",
+        "email": "test@example.com",
+        "phone": "9999999999",
+        "udf1": "Payment Request",
+        "udf2": "PR-0001",
+        "udf3": "",
+        "udf4": "",
+        "udf5": "",
+        "key": "merchant",
+        "surl": "https://example.com/success",
+        "furl": "https://example.com/failure",
+    }
+    seq = "udf10|udf9|udf8|udf7|udf6|udf5|udf4|udf3|udf2|udf1|email|firstname|productinfo|amount|txnid|key".split("|")
+    reverse = salt + "|" + data["status"]
+    for field in seq:
+        reverse += "|" + str(data.get(field, ""))
+    data["hash"] = sha512(reverse.encode("utf-8")).hexdigest().lower()
+    return data
+
+
+payload = build_callback_payload()
+assert payment.easebuzzResponse(payload, "secret")["status"] == 1
+
+with patch("easebuzz.easebuzz.utils.http.requests.post") as mocked:
+    mocked.side_effect = [
+        requests.Timeout(),
+        type("Resp", (), {"status_code": 200, "content": b"{}"})(),
+    ]
+    response = post_with_retries("https://example.com", {"a": 1}, max_attempts=2, backoff_seconds=0)
+    assert response.status_code == 200
+
+print("security smoke checks passed")