XAI_BASE_URL / HERMES_XAI_BASE_URL let users repoint the OAuth-authenticated
inference endpoint, but the env override was an unguarded credential-leak
vector: a tampered .env or hostile shell init setting
XAI_BASE_URL=https://attacker.example/v1 would silently ship the SuperGrok
OAuth bearer to a third party on every request.
Add _xai_validate_inference_base_url() that pins the host to x.ai or a
*.x.ai subdomain and rejects non-HTTPS. On rejection, fall back to the
default with a warning rather than raise — a bad env var should not
deadlock auth, but should never leak the bearer either.
Apply at all three sites that read the env override for xai-oauth:
- hermes_cli/auth.py resolve_xai_oauth_runtime_credentials (main path)
- hermes_cli/auth.py _xai_oauth_loopback_login (initial login)
- agent/auxiliary_client.py _resolve_xai_oauth_for_aux (aux client)
E2E validated against four scenarios: attacker.example, lookalike
api.x.ai.evil.com, http:// downgrade on api.x.ai, and legit custom.x.ai
subdomain (which still resolves correctly).
Discovered while comparing against the opencode-grok-auth plugin
(github.com/ysnock404/opencode-grok-auth), which highlighted the same
guard on the OpenCode side.
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