GHSA-c5f6-2rm9-2w8g

## Summary The OpenChoreo autobuild webhook endpoint (`POST /api/v1alpha1/autobuild`) selected the git provider used to authenticate an incoming webhook from a client-supplied request header rather than from the target component's configuration, and its Bitbucket provider accepted requests without a valid signature. A caller could set the `X-Event-Key` header to be treated as a Bitbucket webhook, bypassing the HMAC secret that otherwise protects GitHub and GitLab webhooks, and trigger a component build without authenticating.

## Impact An attacker who can reach the autobuild webhook endpoint and knows the repository URL and branch configured for an auto-build component can trigger a build for that component without authenticating — including components configured for GitHub or GitLab, since the provider used or verification is chosen by the caller rather than by the component's configuration. The triggered build runs against a commit SHA supplied by the attacker, and the component lookup is not scoped to a tenant or namespace, so any auto-build component across the cluster matching the given repository and branch is affected. This can result in unauthorized builds — and, where auto-deploy is configured, unauthorized deployment of attacker-influenced code — and can be used to exhaust build resources through repeated unauthenticated triggering.

The exposure applies to any component with `spec.autoBuild: true`, regardless of which git provider it declares, wherever the autobuild webhook endpoint is network-reachable.

## Patches Fixed in 1.0.3, 1.1.3, and 1.2.0-rc.2. The fix validates Bitbucket webhooks with HMAC-SHA256 against the configured secret using the same verification path as GitHub, requires a configured, non-empty secret for every provider (a missing secret now rejects the request instead of skipping validation), and requires the authenticated provider to match the git provider configured for the matched component. Upgrading is non-disruptive — no component or webhook configuration changes are required beyond the standard upgrade. Upgrade path: 1.1.x → 1.1.3, 1.0.x and earlier → 1.0.3, 1.2 line → 1.2.0-rc.2 or later.