Please do not open a public issue for security vulnerabilities.

Report them privately to security@vengtoo.com. Include:

• A description of the issue and its impact
• A minimal reproduction (code snippet using the SDK is ideal)
• The SDK version

We will acknowledge your report within 3 business days and keep you updated as we work on a fix. We ask that you give us a reasonable window to release a patch before public disclosure, and we will credit you in the release notes unless you prefer otherwise.

The SDK is the client half of an authorization decision, so we treat these as high severity:

• Fail-open behavior — any code path where an infrastructure failure (timeout, 5xx, malformed response) yields an "allowed" result instead of an exception or deny. This includes the FastAPI require() dependency, which must never let a request through on a failed check.
• Credential handling — API keys, OAuth client secrets, or cached access tokens reaching logs, exception messages, or unintended endpoints.
• Delegation lifecycle — a delegation created by with_delegation remaining active past the task boundary without the caller being informed.

• Pass credentials via environment/secret managers, not source code.
• Prefer OAuth client credentials over long-lived API keys — tokens are short-lived and cached in memory only.
• The require() subject extractor defines who you trust: only read identity from sources your authentication layer controls (e.g. request.state.user set by authn middleware), never from client-suppliable data.
• Treat SDK exceptions as denies in your application logic; the SDK never reports "allowed" on failure.

Security fixes are applied to the latest minor release. Older releases receive fixes on a best-effort basis.