fix(api): download attachments instead of rendering them inline

[cavidelizade]

Summary

Attachment uploads don't validate content-type, and ServeFile streamed every object back with Content-Disposition: inline. A member could upload an HTML file (or an SVG with script) and have it execute on the API origin when another member opened the attachment URL.

Linked issues

Closes #328

Type of change

• Bug fix (fix:)

Surface

• API (apps/api/)

What changed

ServeFile now forces Content-Disposition: attachment for the attachments/ prefix, so the browser downloads the file rather than rendering it. The uploads/ prefix (avatars, covers, logos) is validated as images and stays inline.

Test plan

• go build, go vet, go test ./... green
• Reasoning: with Content-Disposition: attachment the browser won't render the response in-page regardless of its declared type, which neutralizes the stored-XSS vector

Note

This is the low-risk mitigation. Validating/allow-listing content-type on upload (like the image path does) would be a good follow-up, but forcing download closes the XSS on its own.

AI assistance

• AI tools were used, tool(s): Claude Code (Opus 4.8), commits carry a Co-Authored-By: trailer

[coderabbitai]

Warning

Review limit reached

@cavidelizade, you've reached your PR review limit, so we couldn't start this review.

Next review available in: 43 minutes

Enable usage-based reviews in Billing to review now. Otherwise, wait until the next included review is available.
You're only billed for reviews past your plan's rate limits ($0.25/file).

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: ec8b6603-b6ad-4b64-a83a-d32dfabc5c1a

📥 Commits

Reviewing files that changed from the base of the PR and between 61bc903 and 30fea0c.

📒 Files selected for processing (1)

• apps/api/internal/handler/upload.go

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}