How to handle a LINE channel access token safely

What an exposed token can enable

Anyone holding a token may call endpoints granted to that channel, including listing or configuring Rich Menus and other available Messaging API operations. Impact depends on the token type and permissions.

If a token appeared in chat, a commit, screenshot, log, or analytics, treat it as compromised and rotate or revoke it. Deleting the message or commit later does not restore secrecy.

Recommended architecture

Rich Menu Studio uses the supplied token for proxied requests and should not persist it in localStorage. Closing the page ends the UI session, but a token shared outside the system still needs rotation.

• Accept tokens only over HTTPS
• Call LINE through a server-side proxy rather than directly from the frontend
• Do not persist tokens in a database or browser storage unless required
• Redact credentials from errors and access logs
• Apply request-size limits, rate limits, and timeouts
• Never send tokens to analytics, error breadcrumbs, or session replay

Choose a token type and lifecycle

Prefer short-lived or stateless tokens when the workflow supports them. For long-running systems, issue credentials server-side and use the platform secret manager instead of shared .env files.

Track credential owner, issue date, rotation date, channel, and purpose without copying the secret into inventory. Revoke access and rotate related tokens when staff or vendors leave.

Incident checklist for token exposure

Fast containment matters more than proving misuse first. Credential rotation is cheaper than recovering a channel after unauthorized changes.

• Revoke or replace the token immediately
• Check Git history, logs, chat, and CI artifacts for exposure
• Review unusual API requests during the incident window
• Update the secret in Vercel or the runtime and redeploy
• Document the incident and add a regression control
• Never reuse the old token even if exposure seems unlikely