CVE-2026-63115

The ActivityPub server (versions 1.0.0 through 1.2.6), a multi-tenant ActivityPub server for Ghost built with Fedify, contains a vulnerability in the Undo handler . This flaw allows a remote federated server to trigger actions as if they originated from a different account, enabling the unfollow ...

CVE-2026-63115 ActivityPub Undo handler can unfollow or remove reposts on behalf of other accounts

ActivityPub is a multi-tenant ActivityPub server for Ghost, built with Fedify. From 1.0.0 until 1.2.6, the Undo handler allows a remote federated server to cause the service to act on a follow or repost as though the activity came from a different account. This permits removal of an existing foll...

CVE-2026-63115: TryGhost ActivityPub: ActivityPub is a multi-tenant ActivityPub server for Ghost, built with Fedify

ActivityPub is a multi-tenant ActivityPub server for Ghost, built with Fedify. From 1.0.0 until 1.2.6, the Undo handler allows a remote federated server to cause the service to act on a follow or repost as though the activity came from a different account. This permits removal of an existing foll...