[Fix] UI logo not showing when UI_LOGO_PATH is a local file path

- Fix /get_image to use mimetypes.guess_type() for correct Content-Type
  instead of hardcoding image/jpeg for all file types (breaks PNG logos
  in strict enterprise proxy environments)
- Fix get_ui_theme_settings to null out logo_url when it is a local
  filesystem path: the browser cannot load local paths as image URLs,
  so the UI must fall back to /get_image which serves local files via
  the UI_LOGO_PATH env var
- Add test covering the local-path nulling behavior

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

litellm/proxy/proxy_server.py

@@ -3,6 +3,7 @@ import copy
 import enum
 import inspect
 import io
+import mimetypes
 import os
 import random
 import secrets
@@ -11061,10 +11062,16 @@ async def get_image():
     logo_path = os.getenv("UI_LOGO_PATH", default_logo)
     verbose_proxy_logger.debug("Reading logo from path: %s", logo_path)
 
+    def _get_image_media_type(path: str) -> str:
+        media_type, _ = mimetypes.guess_type(path)
+        if media_type and media_type.startswith("image/"):
+            return media_type
+        return "image/jpeg"
+
     # If UI_LOGO_PATH points to a local file, serve it directly (skip cache)
     if logo_path != default_logo and not logo_path.startswith(("http://", "https://")):
         if os.path.exists(logo_path):
-            return FileResponse(logo_path, media_type="image/jpeg")
+            return FileResponse(logo_path, media_type=_get_image_media_type(logo_path))
         # Custom path doesn't exist — fall back to default
         verbose_proxy_logger.warning(
             f"UI_LOGO_PATH '{logo_path}' does not exist, falling back to default logo"
@@ -11103,7 +11110,7 @@ async def get_image():
             return FileResponse(default_logo, media_type="image/jpeg")
     else:
         # Return the local image file if the logo path is not an HTTP/HTTPS URL
-        return FileResponse(logo_path, media_type="image/jpeg")
+        return FileResponse(logo_path, media_type=_get_image_media_type(logo_path))
 
 
 @app.get("/get_favicon", include_in_schema=False)

litellm/proxy/ui_crud_endpoints/proxy_setting_endpoints.py

@@ -734,17 +734,28 @@ async def get_ui_theme_settings():
     Note: This endpoint is public (no authentication required) so all users can see custom branding.
     Only the /update/ui_theme_settings endpoint requires authentication for admins to change settings.
     """
+    import os
+
     from litellm.proxy.proxy_server import proxy_config
 
     # Load existing config
     config = await proxy_config.get_config()
 
-    return await _get_settings_with_schema(
+    result = await _get_settings_with_schema(
         settings_key="ui_theme_config",
         settings_class=UIThemeConfig,
         config=config,
     )
 
+    # If logo_url is a local filesystem path (not an HTTP/HTTPS URL), the browser
+    # cannot load it directly as an image src. Null it out so the UI falls back to
+    # calling the /get_image endpoint, which reads UI_LOGO_PATH and serves the file.
+    logo_url = result["values"].get("logo_url")
+    if logo_url and not logo_url.startswith(("http://", "https://")):
+        result["values"]["logo_url"] = None
+
+    return result
+
 
 @router.patch(
     "/update/ui_theme_settings",

tests/test_litellm/proxy/ui_crud_endpoints/test_proxy_setting_endpoints.py

@@ -776,6 +776,22 @@ class TestProxySettingEndpoints:
             == "https://example.com/favicon.ico"
         )
 
+    def test_get_ui_theme_settings_local_path_is_nulled(self, mock_proxy_config):
+        """
+        Local file paths stored in logo_url cannot be loaded by the browser as an image URL.
+        The endpoint should null them out so the UI falls back to /get_image, which reads
+        UI_LOGO_PATH from the environment and serves the file directly.
+        """
+        mock_proxy_config["config"]["litellm_settings"]["ui_theme_config"] = {
+            "logo_url": "/app/company_logo.png",
+        }
+
+        response = client.get("/get/ui_theme_settings")
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["values"]["logo_url"] is None
+
     def test_get_ui_settings(self, mock_auth, monkeypatch):
         """Test retrieving UI settings with allowlist sanitization"""
         from unittest.mock import AsyncMock, MagicMock