Slink before 1.12.3 Missing Authorization on Image Comment Endpoints

Slink before 1.12.3 fails to properly authorize access to image comment endpoints, allowing unauthenticated attackers to read comment threads via GET /api/image/{imageId}/comments and server-sent-events subscriptions. Attackers who obtain image IDs out of band can retrieve full comment threads on public images and subscribe to live comment updates without authentication or authorization checks.

Slink v1.4.9 allows stored cross-site scripting (XSS) via crafted SVG uploads. When a user views the shared image in a new browser tab, the embedded JavaScript executes. The issue affects both authenticated and unauthenticated users.