diff --git a/plugin/idp/oauth2/oauth2.go b/plugin/idp/oauth2/oauth2.go
index 4ab1d12bc..f2282cd3c 100644
--- a/plugin/idp/oauth2/oauth2.go
+++ b/plugin/idp/oauth2/oauth2.go
@@ -6,8 +6,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"log/slog"
 	"net/http"
+	"time"
 
 	"github.com/pkg/errors"
 	"golang.org/x/oauth2"
@@ -79,7 +79,7 @@ func (p *IdentityProvider) ExchangeToken(ctx context.Context, redirectURL, code,
 
 // UserInfo returns the parsed user information using the given OAuth2 token.
 func (p *IdentityProvider) UserInfo(token string) (*idp.IdentityProviderUserInfo, error) {
-	client := &http.Client{}
+	client := &http.Client{Timeout: 10 * time.Second}
 	req, err := http.NewRequest(http.MethodGet, p.config.UserInfoUrl, nil)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to create http request")
@@ -101,7 +101,6 @@ func (p *IdentityProvider) UserInfo(token string) (*idp.IdentityProviderUserInfo
 	if err := json.Unmarshal(body, &claims); err != nil {
 		return nil, errors.Wrap(err, "failed to unmarshal response body")
 	}
-	slog.Info("user info claims", "claims", claims)
 	userInfo := &idp.IdentityProviderUserInfo{}
 	if v, ok := claims[p.config.FieldMapping.Identifier].(string); ok {
 		userInfo.Identifier = v
@@ -129,6 +128,5 @@ func (p *IdentityProvider) UserInfo(token string) (*idp.IdentityProviderUserInfo
 			userInfo.AvatarURL = v
 		}
 	}
-	slog.Info("user info", "userInfo", userInfo)
 	return userInfo, nil
 }
diff --git a/server/router/api/v1/auth_service.go b/server/router/api/v1/auth_service.go
index 87cc55a63..bc45b82f5 100644
--- a/server/router/api/v1/auth_service.go
+++ b/server/router/api/v1/auth_service.go
@@ -83,8 +83,8 @@ func (s *APIV1Service) SignIn(ctx context.Context, request *v1pb.SignInRequest)
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "failed to get instance general setting, error: %v", err)
 		}
-		// Check if the password auth in is allowed.
-		if instanceGeneralSetting.DisallowPasswordAuth && user.Role == store.RoleUser {
+		// Check if password auth is allowed. Enforce for all roles including admins.
+		if instanceGeneralSetting.DisallowPasswordAuth {
 			return nil, status.Errorf(codes.PermissionDenied, "password signin is not allowed")
 		}
 		existingUser = user
diff --git a/server/router/api/v1/user_service.go b/server/router/api/v1/user_service.go
index e718a8b15..8a40cd3fc 100644
--- a/server/router/api/v1/user_service.go
+++ b/server/router/api/v1/user_service.go
@@ -160,6 +160,9 @@ func (s *APIV1Service) CreateUser(ctx context.Context, request *v1pb.CreateUserR
 		}, nil
 	}
 
+	if len(request.User.Password) < 8 {
+		return nil, status.Errorf(codes.InvalidArgument, "password must be at least 8 characters")
+	}
 	passwordHash, err := bcrypt.GenerateFromPassword([]byte(request.User.Password), bcrypt.DefaultCost)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to generate password hash: %v", err)
@@ -269,6 +272,9 @@ func (s *APIV1Service) UpdateUser(ctx context.Context, request *v1pb.UpdateUserR
 			role := convertUserRoleToStore(request.User.Role)
 			update.Role = &role
 		case "password":
+			if len(request.User.Password) < 8 {
+				return nil, status.Errorf(codes.InvalidArgument, "password must be at least 8 characters")
+			}
 			passwordHash, err := bcrypt.GenerateFromPassword([]byte(request.User.Password), bcrypt.DefaultCost)
 			if err != nil {
 				return nil, status.Errorf(codes.Internal, "failed to generate password hash: %v", err)
diff --git a/server/router/api/v1/v1.go b/server/router/api/v1/v1.go
index 79c140f07..74645d54c 100644
--- a/server/router/api/v1/v1.go
+++ b/server/router/api/v1/v1.go
@@ -115,7 +115,17 @@ func (s *APIV1Service) RegisterGateway(ctx context.Context, echoServer *echo.Ech
 	}
 	gwGroup := echoServer.Group("")
 	gwGroup.Use(middleware.CORSWithConfig(middleware.CORSConfig{
-		AllowOrigins: []string{"*"},
+		UnsafeAllowOriginFunc: func(_ *echo.Context, origin string) (string, bool, error) {
+			// In demo mode, allow all origins for development convenience.
+			// In production, deny cross-origin requests (same-origin only).
+			if s.Profile.Demo {
+				return origin, true, nil
+			}
+			return "", false, nil
+		},
+		AllowMethods:     []string{http.MethodGet, http.MethodPost, http.MethodPut, http.MethodPatch, http.MethodDelete, http.MethodOptions},
+		AllowHeaders:     []string{"Content-Type", "Authorization"},
+		AllowCredentials: true,
 	}))
 	// Register SSE endpoint with same CORS as rest of /api/v1.
 	gwGroup.GET("/api/v1/sse", func(c *echo.Context) error {
@@ -141,7 +151,11 @@ func (s *APIV1Service) RegisterGateway(ctx context.Context, echoServer *echo.Ech
 	// Wrap with CORS for browser access
 	corsHandler := middleware.CORSWithConfig(middleware.CORSConfig{
 		UnsafeAllowOriginFunc: func(_ *echo.Context, origin string) (string, bool, error) {
-			return origin, true, nil
+			// In demo mode, allow all origins for development convenience.
+			if s.Profile.Demo {
+				return origin, true, nil
+			}
+			return "", false, nil
 		},
 		AllowMethods:     []string{http.MethodGet, http.MethodPost, http.MethodOptions},
 		AllowHeaders:     []string{"*"},
diff --git a/server/server.go b/server/server.go
index dd3247def..1b6ab3ba1 100644
--- a/server/server.go
+++ b/server/server.go
@@ -50,11 +50,9 @@ func NewServer(ctx context.Context, profile *profile.Profile, store *store.Store
 		return nil, errors.Wrap(err, "failed to get instance basic setting")
 	}
 
-	secret := "usememos"
-	if !profile.Demo {
-		secret = instanceBasicSetting.SecretKey
-	}
-	s.Secret = secret
+	// Always use the instance secret key, regardless of mode.
+	// Never fall back to a hardcoded secret, as it allows token forgery.
+	s.Secret = instanceBasicSetting.SecretKey
 
 	// Register healthz endpoint.
 	echoServer.GET("/healthz", func(c *echo.Context) error {