CVE-2026-43890 Outline: IDOR in subscriptions.create allows cross-tenant subscription on private documents (sibling of GHSA-23jj-rp48-w7q7)

Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.7.0, the subscriptions.create API endpoint in server/routes/api/subscriptions/subscriptions.ts exhibits a broken authorization pattern. When both collectionId and documentId are supplied in the request, the route...