CVE-2026-54096: File Browser: Improper Access Control Occurs via Pre-Created Public Share for a Non-existent Path

This is similar vulnrability of CVE-2026-0035, which was fixed in Android MediaProvider with high severity. In the original Java issue, MediaStore.createWriteRequest() accepted attacker-controlled URIs and created a future grant even when the referenced media item did not exist yet. The Android fix added an existence check before creating the request.

filebrowser/filebrowser has the analogous issue in Go. POST /api/share/<path> accepts an authenticated request for an arbitrary path and stores a public share record without checking whether the target file currently exists. Later, when a file is created at that same path, the previously created public share immediately becomes valid and exposes the new file through GET /api/public/dl/<hash>.