diff --git a/descope/common.py b/descope/common.py
index abe045c24..0f7a9ae7a 100644
--- a/descope/common.py
+++ b/descope/common.py
@@ -8,7 +8,10 @@
 DEFAULT_BASE_URL = DEFAULT_URL_PREFIX + "." + DEFAULT_DOMAIN  # pragma: no cover
 DEFAULT_TIMEOUT_SECONDS = 60
 
-PHONE_REGEX = r"""^(?:(?:\(?(?:00|\+)([1-4]\d\d|[1-9]\d?)\)?)?[\-\.\ \\/]?)?((?:\(?\d{1,}\)?[\-\.\ \\/]?){0,})(?:[\-\.\ \\/]?(?:#|ext\.?|extension|x)[\-\.\ \\/]?(\d+))?$"""
+# Simple phone validation to prevent ReDoS (catastrophic backtracking)
+# Optional leading +, then digits, spaces, hyphens, parentheses, dots, # for extension
+# Requires at least 4 consecutive digits, length 7-25, at most one leading +
+PHONE_REGEX = r"""^(?=.*\d{4,})\+?[\d\s\-\(\)\.#xX]{6,24}$"""
 
 SESSION_COOKIE_NAME = "DS"
 REFRESH_SESSION_COOKIE_NAME = "DSR"
diff --git a/descope/descope_client.py b/descope/descope_client.py
index 610400901..3a07b01b2 100644
--- a/descope/descope_client.py
+++ b/descope/descope_client.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import os
+import warnings
 from typing import Iterable
 
 import requests
@@ -50,6 +51,17 @@ def __init__(
                 ),
             )
 
+        # Warn about TLS verification bypass
+        if skip_verify:
+            warnings.warn(
+                "⚠️  SECURITY WARNING: TLS certificate verification is DISABLED (skip_verify=True). "
+                "This makes your application vulnerable to man-in-the-middle attacks. "
+                "ONLY use this for local development with self-signed certificates. "
+                "NEVER use skip_verify=True in production environments.",
+                category=UserWarning,
+                stacklevel=2,
+            )
+
         # Auth Initialization
         auth_http_client = HTTPClient(
             project_id=project_id,
diff --git a/descope/flask/__init__.py b/descope/flask/__init__.py
index aab97141b..a0296e04f 100644
--- a/descope/flask/__init__.py
+++ b/descope/flask/__init__.py
@@ -34,7 +34,7 @@ def set_cookie_on_response(response: Response, token: dict, cookie_data: dict):
         expires=cookie_data.get("exp", expire_time),
         path=cookie_data.get("path", "/"),
         domain=cookie_domain,
-        secure=False,  # True
+        secure=True,  # Cookies must be sent over HTTPS only
         httponly=True,
         samesite="Strict",  # "Strict", "Lax", "None"
     )
diff --git a/descope/jwt_common.py b/descope/jwt_common.py
index 2183df5ea..500f047c7 100644
--- a/descope/jwt_common.py
+++ b/descope/jwt_common.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import warnings
 from typing import Callable, Iterable, Optional
 
 import jwt
@@ -71,9 +72,20 @@ def decode_token_unverified(
 ) -> dict:
     """Decode a JWT without verifying signature (used when no validator is provided).
 
+    WARNING: This function does NOT verify JWT signatures and should NEVER be used
+    for authentication or authorization decisions. It is only intended for testing
+    or scenarios where token validation happens elsewhere.
+
     Audience verification is disabled by default since no key is provided.
     Returns an empty dict if decoding fails.
     """
+    warnings.warn(
+        "decode_token_unverified() does not verify JWT signatures. "
+        "Do not use this for authentication or authorization. "
+        "Use proper token validation with signature verification instead.",
+        UserWarning,
+        stacklevel=2,
+    )
     try:
         return jwt.decode(
             token, options={"verify_signature": False, "verify_aud": False}
diff --git a/samples/otp_web_sample_app.py b/samples/otp_web_sample_app.py
index e0ce2cddb..7f43f33f7 100644
--- a/samples/otp_web_sample_app.py
+++ b/samples/otp_web_sample_app.py
@@ -18,7 +18,9 @@
 
 PROJECT_ID = ""
 
-# init the DescopeClient
+# SECURITY WARNING: skip_verify=True disables TLS certificate verification
+# ONLY use this for local development with self-signed certificates
+# NEVER use skip_verify=True in production - remove this parameter for production
 descope_client = DescopeClient(PROJECT_ID, skip_verify=True)
 
 
diff --git a/samples/password_web_sample_app.py b/samples/password_web_sample_app.py
index 13575c064..c3aaf44a3 100755
--- a/samples/password_web_sample_app.py
+++ b/samples/password_web_sample_app.py
@@ -14,7 +14,9 @@
 
 PROJECT_ID = ""
 
-# init the DescopeClient
+# SECURITY WARNING: skip_verify=True disables TLS certificate verification
+# ONLY use this for local development with self-signed certificates
+# NEVER use skip_verify=True in production - remove this parameter for production
 descope_client = DescopeClient(PROJECT_ID, skip_verify=True)
 
 
diff --git a/tests/test_jwt_common.py b/tests/test_jwt_common.py
index a6b9c7add..9cfb47e6a 100644
--- a/tests/test_jwt_common.py
+++ b/tests/test_jwt_common.py
@@ -1,4 +1,5 @@
 import unittest
+import warnings
 
 from descope.jwt_common import (
     COOKIE_DATA_NAME,
@@ -58,7 +59,9 @@ def validator(token: str, audience=None):
 
     def test_decode_token_unverified_handles_garbage(self):
         # Invalid token strings should not raise and should return empty dict
-        assert decode_token_unverified("not-a-jwt") == {}
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", UserWarning)
+            assert decode_token_unverified("not-a-jwt") == {}
 
 
 if __name__ == "__main__":