From ea097ab6f0f56332dac2dfdd2caa2782d42a9911 Mon Sep 17 00:00:00 2001
From: Herculino Trotta <hello@herculino.com>
Date: Sun, 15 Feb 2026 14:41:45 -0300
Subject: [PATCH] feat(auth): trust OIDC connections and connect them with
 local accounts

---
 README.md                  |  7 ++++
 app/WYGIWYH/settings.py    |  4 +-
 app/apps/users/adapters.py | 75 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 1 deletion(-)
 create mode 100644 app/apps/users/adapters.py

diff --git a/README.md b/README.md
index 9835c2b..49123e8 100644
--- a/README.md
+++ b/README.md
@@ -157,6 +157,13 @@ WYGIWYH supports login via OpenID Connect (OIDC) through `django-allauth`. This
 > [!NOTE]
 > Currently only OpenID Connect is supported as a provider, open an issue if you need something else.
 
+> [!Caution]
+> WYGIWYH automatically connects OIDC accounts to existing local accounts with matching email addresses.
+> This means if a user already exists with email `user@example.com` and someone logs in via OIDC with the same email, the OIDC account will be automatically linked to the existing account without requiring user confirmation.
+> This is only recommended for trusted OIDC providers that verify email addresses and where you control who can create accounts.
+
+### Configuration
+
 To configure OIDC, you need to set the following environment variables:
 
 | Variable             | Description                                                                                                                                                                                                                                            |
diff --git a/app/WYGIWYH/settings.py b/app/WYGIWYH/settings.py
index eead651..0cf8373 100644
--- a/app/WYGIWYH/settings.py
+++ b/app/WYGIWYH/settings.py
@@ -375,8 +375,10 @@ ACCOUNT_EMAIL_VERIFICATION = "none"
 SOCIALACCOUNT_LOGIN_ON_GET = True
 SOCIALACCOUNT_ONLY = True
 SOCIALACCOUNT_AUTO_SIGNUP = os.getenv("OIDC_ALLOW_SIGNUP", "true").lower() == "true"
+SOCIALACCOUNT_EMAIL_AUTHENTICATION = True
+SOCIALACCOUNT_EMAIL_AUTHENTICATION_AUTO_CONNECT = True
 ACCOUNT_ADAPTER = "allauth.account.adapter.DefaultAccountAdapter"
-SOCIALACCOUNT_ADAPTER = "allauth.socialaccount.adapter.DefaultSocialAccountAdapter"
+SOCIALACCOUNT_ADAPTER = "apps.users.adapters.AutoConnectSocialAccountAdapter"
 
 # CRISPY FORMS
 CRISPY_ALLOWED_TEMPLATE_PACKS = [
diff --git a/app/apps/users/adapters.py b/app/apps/users/adapters.py
new file mode 100644
index 0000000..41b02c1
--- /dev/null
+++ b/app/apps/users/adapters.py
@@ -0,0 +1,75 @@
+import logging
+from allauth.socialaccount.adapter import DefaultSocialAccountAdapter
+from django.contrib.auth import get_user_model
+
+User = get_user_model()
+logger = logging.getLogger(__name__)
+
+
+class AutoConnectSocialAccountAdapter(DefaultSocialAccountAdapter):
+    """
+    Custom adapter to automatically connect social accounts to existing users
+    with the same email address.
+
+    SECURITY WARNING:
+    This adapter automatically connects OIDC accounts to existing local accounts
+    based on email matching.
+
+    If your OIDC provider allows unverified emails, this could lead to
+    ACCOUNT TAKEOVER attacks where an attacker creates an OIDC account
+    with someone else's email and gains access to their account.
+    """
+
+    def pre_social_login(self, request, sociallogin):
+        """
+        Invoked just after a user successfully authenticates via a
+        social provider, but before the login is actually processed.
+
+        If a user with the same email already exists, connect the social
+        account to that existing user instead of creating a new account.
+        """
+        # If the social account is already connected to a user, do nothing
+        if sociallogin.is_existing:
+            return
+
+        # Check if we have an email from the social provider
+        if not sociallogin.email_addresses:
+            logger.warning(
+                "OIDC login attempted without email address. "
+                f"Provider: {sociallogin.account.provider}"
+            )
+            return
+
+        # Get the email from the social login
+        email = sociallogin.email_addresses[0].email.lower()
+
+        # Try to find an existing user with this email
+        try:
+            user = User.objects.get(email__iexact=email)
+
+            # Log this connection for security audit trail
+            logger.info(
+                f"Auto-connecting OIDC account to existing user. "
+                f"Email: {email}, Provider: {sociallogin.account.provider}, "
+                f"User ID: {user.id}"
+            )
+
+            # Connect the social account to the existing user
+            sociallogin.connect(request, user)
+
+        except User.DoesNotExist:
+            # No user with this email exists, proceed with normal signup flow
+            logger.debug(
+                f"No existing user found for email {email}. "
+                "Proceeding with new account creation."
+            )
+            pass
+        except User.MultipleObjectsReturned:
+            # Multiple users with the same email (shouldn't happen with unique constraint)
+            logger.error(
+                f"Multiple users found with email {email}. "
+                "This should not happen with unique constraint. "
+                "Blocking auto-connect."
+            )
+            # Let the default behavior handle this
+            pass