litellm - 💡(How to fix) Fix [Feature]: Per-deployment option to drop specific inbound client headers [1 participants]

Check for existing issues

• I have searched the existing issues and checked that my issue is not a duplicate.

The Feature

Add an additional_drop_headers field to litellm_params in model_list entries, mirroring the existing additional_drop_params pattern.

  model_list:
    - model_name: claude-opus-4-7
      litellm_params:
        model: bedrock/anthropic.claude-opus-4-7-v1:0
        additional_drop_headers:
          - authorization
          - anthropic-beta
          - anthropic-version

Scope (important): this only filters headers that were forwarded from the client → LiteLLM (typically via forward_client_headers_to_llm_api: true).

It does not touch any headers LiteLLM itself generates when calling the upstream provider (e.g. AWS SigV4 Authorization, the provider's own auth, anthropic-version set by the Anthropic transformer, etc.). So request-building / signing on the LiteLLM → upstream leg is unaffected.

Motivation, pitch

With forward_client_headers_to_llm_api: true, headers a client sends to LiteLLM are carried through to backend calls including the fallback call. That's where cross-provider conflicts surface.

Concrete example we hit in production:

1. Claude Code authenticates via Claude subscription OAuth, sends Authorization: Bearer sk-ant-oat01-... to LiteLLM.
2. Primary anthropic/claude-opus-* succeeds → subscription quota is consumed.
3. On rate_limit_error, the router falls back to bedrock/anthropic.claude-opus-*.
4. The same client Authorization header is still in the request data on the fallback hop. AWS SigV4 signing collides with the pre-existing Bearer value, and Bedrock rejects

Invalid key=value pair (missing equal-sign) in Authorization header
(hashed with SHA-256 and encoded with Base64): '…='

What part of LiteLLM is this about?

Proxy

LiteLLM is hiring a founding backend engineer, are you interested in joining us and shipping to all our users?

No

Twitter / LinkedIn details

https://www.linkedin.com/in/%EC%84%B8%ED%99%98-%EA%B9%80-a31543202/