diff --git a/api/controllers/inner_api/plugin/wraps.py b/api/controllers/inner_api/plugin/wraps.py
index 89b4ac7506..f751e06ddf 100644
--- a/api/controllers/inner_api/plugin/wraps.py
+++ b/api/controllers/inner_api/plugin/wraps.py
@@ -8,37 +8,44 @@ from flask_restx import reqparse
 from pydantic import BaseModel
 from sqlalchemy.orm import Session
 
+from core.file.constants import DEFAULT_SERVICE_API_USER_ID
 from extensions.ext_database import db
 from libs.login import _get_user
-from models.account import Account, Tenant
+from models.account import Tenant
 from models.model import EndUser
-from services.account_service import AccountService
 
 
-def get_user(tenant_id: str, user_id: str | None) -> Account | EndUser:
+def get_user(tenant_id: str, user_id: str | None) -> EndUser:
+    """
+    Get current user
+
+    NOTE: user_id is not trusted, it could be maliciously set to any value.
+    As a result, it could only be considered as an end user id.
+    """
     try:
         with Session(db.engine) as session:
             if not user_id:
-                user_id = "DEFAULT-USER"
+                user_id = DEFAULT_SERVICE_API_USER_ID
+
+            user_model = (
+                session.query(EndUser)
+                .where(
+                    EndUser.session_id == user_id,
+                    EndUser.tenant_id == tenant_id,
+                )
+                .first()
+            )
+            if not user_model:
+                user_model = EndUser(
+                    tenant_id=tenant_id,
+                    type="service_api",
+                    is_anonymous=user_id == DEFAULT_SERVICE_API_USER_ID,
+                    session_id=user_id,
+                )
+                session.add(user_model)
+                session.commit()
+                session.refresh(user_model)
 
-            if user_id == "DEFAULT-USER":
-                user_model = session.query(EndUser).where(EndUser.session_id == "DEFAULT-USER").first()
-                if not user_model:
-                    user_model = EndUser(
-                        tenant_id=tenant_id,
-                        type="service_api",
-                        is_anonymous=True if user_id == "DEFAULT-USER" else False,
-                        session_id=user_id,
-                    )
-                    session.add(user_model)
-                    session.commit()
-                    session.refresh(user_model)
-            else:
-                user_model = AccountService.load_user(user_id)
-                if not user_model:
-                    user_model = session.query(EndUser).where(EndUser.id == user_id).first()
-                if not user_model:
-                    raise ValueError("user not found")
     except Exception:
         raise ValueError("user not found")
 
@@ -63,7 +70,7 @@ def get_user_tenant(view: Optional[Callable] = None):
                 raise ValueError("tenant_id is required")
 
             if not user_id:
-                user_id = "DEFAULT-USER"
+                user_id = DEFAULT_SERVICE_API_USER_ID
 
             del kwargs["tenant_id"]
             del kwargs["user_id"]
diff --git a/api/controllers/service_api/wraps.py b/api/controllers/service_api/wraps.py
index 2df00d9fc7..14291578d5 100644
--- a/api/controllers/service_api/wraps.py
+++ b/api/controllers/service_api/wraps.py
@@ -13,6 +13,7 @@ from sqlalchemy import select, update
 from sqlalchemy.orm import Session
 from werkzeug.exceptions import Forbidden, NotFound, Unauthorized
 
+from core.file.constants import DEFAULT_SERVICE_API_USER_ID
 from extensions.ext_database import db
 from extensions.ext_redis import redis_client
 from libs.datetime_utils import naive_utc_now
@@ -271,7 +272,7 @@ def create_or_update_end_user_for_user_id(app_model: App, user_id: Optional[str]
     Create or update session terminal based on user ID.
     """
     if not user_id:
-        user_id = "DEFAULT-USER"
+        user_id = DEFAULT_SERVICE_API_USER_ID
 
     with Session(db.engine, expire_on_commit=False) as session:
         end_user = (
@@ -290,7 +291,7 @@ def create_or_update_end_user_for_user_id(app_model: App, user_id: Optional[str]
                 tenant_id=app_model.tenant_id,
                 app_id=app_model.id,
                 type="service_api",
-                is_anonymous=user_id == "DEFAULT-USER",
+                is_anonymous=user_id == DEFAULT_SERVICE_API_USER_ID,
                 session_id=user_id,
             )
             session.add(end_user)
diff --git a/api/core/file/constants.py b/api/core/file/constants.py
index 0665ed7e0d..ed1779fd13 100644
--- a/api/core/file/constants.py
+++ b/api/core/file/constants.py
@@ -9,3 +9,7 @@ FILE_MODEL_IDENTITY = "__dify__file__"
 
 def maybe_file_object(o: Any) -> bool:
     return isinstance(o, dict) and o.get("dify_model_identity") == FILE_MODEL_IDENTITY
+
+
+# The default user ID for service API calls.
+DEFAULT_SERVICE_API_USER_ID = "DEFAULT-USER"
diff --git a/api/core/file/helpers.py b/api/core/file/helpers.py
index 335ad2266a..3ec29fe23d 100644
--- a/api/core/file/helpers.py
+++ b/api/core/file/helpers.py
@@ -5,6 +5,7 @@ import os
 import time
 
 from configs import dify_config
+from core.file.constants import DEFAULT_SERVICE_API_USER_ID
 
 
 def get_signed_file_url(upload_file_id: str) -> str:
@@ -26,7 +27,7 @@ def get_signed_file_url_for_plugin(filename: str, mimetype: str, tenant_id: str,
     url = f"{base_url}/files/upload/for-plugin"
 
     if user_id is None:
-        user_id = "DEFAULT-USER"
+        user_id = DEFAULT_SERVICE_API_USER_ID
 
     timestamp = str(int(time.time()))
     nonce = os.urandom(16).hex()
@@ -42,7 +43,7 @@ def verify_plugin_file_signature(
     *, filename: str, mimetype: str, tenant_id: str, user_id: str | None, timestamp: str, nonce: str, sign: str
 ) -> bool:
     if user_id is None:
-        user_id = "DEFAULT-USER"
+        user_id = DEFAULT_SERVICE_API_USER_ID
 
     data_to_sign = f"upload|{filename}|{mimetype}|{tenant_id}|{user_id}|{timestamp}|{nonce}"
     secret_key = dify_config.SECRET_KEY.encode()