Filecoin Pin is an IPFS Pinning Service API implementation that pins to Filecoin's PDP service. Prior to 1.1.0, the upload GitHub Action's fork detection in `upload-action/src/build.js` checks only `event.pull_request`. In the documented two-workflow pattern, an untrusted fork pull-request workflow produces an artifact and a privileged `workflow_run` workflow downloads and uploads it. Because `workflow_run` has no `event.pull_request`, `isForkPR` becomes false and `uploadStatus` becomes `pending-upload`. The action later resolves `workflow_run.pull_requests` without repeating the fork check before initializing the wallet with `walletPrivateKey` and uploading the artifact. An external contributor can therefore cause attacker-controlled artifacts to be stored using the repository owner's Filecoin wallet, incurring unauthorized storage expenditure, dataset pollution and consumption of configured wallet funds. Disclosure of the wallet private key is not required. The 0.x action line is not receiving a backport and must be migrated to a fixed 1.x release. This issue is fixed in version 1.1.0.