QStash Tokens Leaked via NEXT_PUBLIC_ Prefix

Upstash QStash is a great serverless job queue. It uses a bearer token that grants publish rights to your queue topics. The generator pattern from AI tools sometimes looks like:

NEXT_PUBLIC_QSTASH_TOKEN=eyJ...

This is the worst-possible name for this value. The NEXT_PUBLIC_ prefix is Next.js's explicit opt-in to client exposure. Rename and rotate.

Detect

curl -s https://your-app.com/_next/static/chunks/*.js |   grep -oE "eyJ[A-Za-z0-9_-]{80,}"  # QStash tokens look like JWTs

Any JWT-like blob in the bundle that is NOT your Clerk/Auth0 public key is suspect.

Impact

• Attacker publishes arbitrary events to your queue.
• Your queued handlers act on them — expensive ones (send email, run AI prompt, charge Stripe).
• Quota exhausted, bill inflated, possibly trust in queue handlers compromised.

Fix

1. Rotate the token in Upstash.
2. Rename env to QSTASH_TOKEN (server-only).
3. Move every usage to app/api/* route handlers or server actions.
4. Add Verify Signature on the QStash callback side so even leaked tokens can't push rogue events back to you.