fix: resolve terminal system_oauth token server-side instead of trusting a client header (#26719)

The terminal proxy's system_oauth auth type read the OAuth access token from the client-supplied x-oauth-access-token request header and forwarded it verbatim as a Bearer token to the upstream terminal server, so an authenticated caller could substitute an arbitrary token for the one bound to their own session. Resolve the token server-side from the caller's OAuth session via oauth_manager.get_oauth_token(user.id, oauth_session_id), matching the openai.py proxy, so the forwarded token is always the one Open WebUI issued for the authenticated user and the client header is ignored.

Co-authored-by: brodmart <brodmart@users.noreply.github.com>

backend/open_webui/routers/terminals.py

@@ -132,9 +132,18 @@ async def proxy_terminal(
         headers.update(bearer_auth_header(request.state.token.credentials))
     elif auth_type == 'system_oauth':
         cookies = request.cookies
-        oauth_token = request.headers.get('x-oauth-access-token', '')
+        # Resolve the token server-side from the caller's OAuth session; never trust a client header.
+        oauth_token = None
+        try:
+            if request.cookies.get('oauth_session_id', None):
+                oauth_token = await request.app.state.oauth_manager.get_oauth_token(
+                    user.id,
+                    request.cookies.get('oauth_session_id', None),
+                )
+        except Exception as e:
+            log.error(f'Error getting OAuth token: {e}')
         if oauth_token:
-            headers.update(bearer_auth_header(oauth_token))
+            headers.update(bearer_auth_header(oauth_token.get('access_token', '')))
     # auth_type == "none": no Authorization header
 
     content_type = request.headers.get('content-type')