LiteLLM: Privilege escalation via unrestricted proxy configuration endpoint

### Impact The `/config/update endpoint` does not enforce admin role authorization. A user who is already authenticated into the platform can then use this endpoint to do the following: - Modify proxy configuration and environment variables - Register custom pass-through endpoint handlers pointing to attacker-controlled Python code, achieving remote code execution - Read arbitrary server files by setting UI_LOGO_PATH and fetching via /get_image - Take over other priveleged accounts by overwriting UI_USERNAME and UI_PASSWORD environment variables ### Patches Fixed in v1.83.0. The endpoint now requires `proxy_admin` role. ### Workarounds Restrict API key distribution. There is no configuration-level workaround.