POST /api/v1/uploads minted an upload key from caller input with no
ownership check, no content-type allowlist, and the raw filename
interpolated into the S3 key.
- Ownership: a caller may only mint upload URLs for a route/activity
they own, enforced via the branded loadOwnedRoute/loadOwnedActivity
(404 on miss, no existence leak). Closes writing into another
user's resource key-space.
- Content type: the request schema now constrains contentType to an
image/gpx allowlist, so active content (HTML/SVG/JS) that would
execute if served inline is rejected at the request boundary.
- Filename: sanitizeUploadFilename() reduces the client filename to a
safe basename (charset-restricted, no path components, no leading
dots, length-bounded) before it becomes part of the key.
Tests: schema allow/deny + filename sanitization in @trails-cool/api;
handler tests covering owned-success, not-owner 404, disallowed
content-type, and the route-vs-activity ownership branch.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
