BerriAI/litellm · error · ValueError

advisor tool definition sets 'api_base' but the proxy has TL

Error message

advisor tool definition sets 'api_base' but the proxy has TLS verification disabled (litellm.ssl_verify=False), so a caller-supplied api_base can't be safely validated against DNS rebinding.

What it means

Third guard in the advisor credential chain: a caller-supplied api_base is refused when litellm.ssl_verify is False. With TLS verification disabled, certificate validation cannot block DNS-rebinding attacks against the https-scheme check, so the resolver refuses the combination rather than ship an unsafe path. Note disabling ssl_verify globally also disables this feature.

Source

Thrown at litellm/llms/anthropic/experimental_pass_through/messages/interceptors/advisor.py:223

    ``anthropic_messages()`` call chain.
    """
    if not _allow_client_side_advisor_credentials():
        return None, None
    api_key: Final[str | None] = advisor_tool.get("api_key")
    api_base: Final[str | None] = advisor_tool.get("api_base")
    if api_base is None:
        return api_key, None
    if not api_key:
        raise ValueError(
            "advisor tool definition sets 'api_base' without 'api_key'. A "
            "caller-supplied api_base is only honored alongside a "
            "caller-supplied api_key, so the proxy's own credentials are "
            "never sent to a caller-chosen destination."
        )
    if not api_base.startswith("https://"):
        raise ValueError(f"advisor tool definition sets 'api_base'={api_base!r}, which must use the https scheme.")
    if getattr(litellm, "ssl_verify", True) is False:
        raise ValueError(
            "advisor tool definition sets 'api_base' but the proxy has TLS verification "
            "disabled (litellm.ssl_verify=False), so a caller-supplied api_base can't be "
            "safely validated against DNS rebinding."
        )
    if getattr(litellm, "user_url_validation", True):
        validate_url(api_base)
    return api_key, api_base


def _make_synthetic_advisor_tool() -> dict:
    """Build a regular tool definition the executor provider can understand."""
    return {
        "name": "advisor",
        "description": ADVISOR_TOOL_DESCRIPTION,
        "input_schema": {
            "type": "object",
            "properties": {
                "question": {

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Re-enable TLS verification (remove litellm.ssl_verify = False) and add the internal CA / self-signed cert to the trust store (e.g. via REQUESTS_CA_BUNDLE or SSL_CERT_FILE).
2. Or terminate TLS properly for the destination with a publicly trusted cert.
3. Or move the destination into server-side proxy config where credentials are gateway-owned, avoiding caller-supplied api_base entirely.

Example fix

# before
import litellm
litellm.ssl_verify = False  # breaks caller-supplied advisor api_base

# after
import os
os.environ["REQUESTS_CA_BUNDLE"] = "/path/to/internal-ca.pem"  # trust the internal CA instead

import litellm

def advisor_custom_base_allowed() -> bool:
    return getattr(litellm, "ssl_verify", True) is not False

def advisor_config_is_safe(advisor_tool: dict, ssl_verify: bool = True) -> bool:
    api_base = advisor_tool.get("api_base")
    if api_base is None:
        return True
    return ssl_verify and api_base.startswith("https://") and bool(advisor_tool.get("api_key"))

try:
    resp = litellm.anthropic_messages(tools=tools, ...)
except ValueError as e:
    if "TLS verification disabled" in str(e):
        return http_error(400, "caller-supplied api_base requires ssl_verify=True")
    raise

When it happens

Trigger: Advisor tool with api_base (https) and api_key, while the process runs with litellm.ssl_verify = False (commonly set to tolerate self-signed certificates in dev). getattr(litellm, 'ssl_verify', True) is False and the ValueError fires.

Common situations: Dev environments with self-signed certs where developers set litellm.ssl_verify=False as a workaround; CI pipelines that disable verification globally; the same flag set to work with other self-signed providers breaking advisor custom bases.

Understand the failure class

• SSL/TLS and certificate errors — how TLS handshakes and certificate validation fail.

Related errors

• advisor tool definition sets 'api_base' without 'api_key'. A
• advisor tool definition sets 'api_base'={api_base!r}, which
• URL targets a blocked address ({resolved_ip}). If this is a
• Advisor tool must have a valid model
• advisor tool definition must include a 'model' field specify

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/0ce0b41c17854940. Report an issue: GitHub.