Slack Incoming Webhook URL Exposed
A Slack incoming webhook URL is public. The URL is the only credential it has, so anyone who copies it can post messages into that channel as your app. The realistic abuse is phishing your own team from a source they trust, or flooding the channel to bury real alerts.
Why it matters
A Slack incoming webhook URL is public. The URL is the only credential it has, so anyone who copies it can post messages into that channel as your app. The realistic abuse is phishing your own team from a source they trust, or flooding the channel to bury real alerts.
How ShipReady detects it
Detects credentials that reached the browser. Scans the page HTML and every linked JavaScript bundle for the literal shapes real provider keys take — `sk_live_`, `AKIA`, `ghp_`, a JWT with a service_role claim — rather than guessing from entropy. High-entropy string detection finds build hashes, CSS class names and base64 images on almost every site; provider prefixes are unambiguous, which is why this check reports only what it can name. A match is evidence, not inference: the value was served to anyone who loaded the page. Evidence records the variable NAME and a ten-character prefix, never the key, because a report that quoted the secret would republish it. Bundles are fetched once per scan and shared across pages, so a key present in a chunk loaded on ten routes is reported once.
Detection is deterministic. ShipReady reports this only when it observes the condition directly, and prefers to miss a real problem over inventing one. Rule version 1.4.0.
How to fix it
This is the prompt ShipReady puts in your report — written to be pasted straight into Cursor, Claude Code, or whichever assistant built the app.
Delete this webhook and create a new one: api.slack.com/apps -> your app -> Incoming Webhooks -> remove the exposed URL and add a fresh one. The URL is itself the credential, so rotating it is the only fix. Send Slack messages from a server endpoint instead of the browser, so the new URL is never shipped to clients.
Frequently asked questions
- What does "Slack Incoming Webhook URL Exposed" mean?
- A Slack incoming webhook URL is public. The URL is the only credential it has, so anyone who copies it can post messages into that channel as your app. The realistic abuse is phishing your own team from a source they trust, or flooding the channel to bury real alerts.
- How serious is it?
- ShipReady rates this high. Fix before launch. A real weakness that an attacker can act on.
- How do I fix it?
- Paste the fix prompt on this page into Cursor, Claude Code or your AI editor. It is the same prompt ShipReady puts in your report.
- Can I check my own site?
- Yes — ShipReady scans up to ten pages of any public site for free and reports this alongside every other check.
Related checks
Does your site have this?
ShipReady checks this and 73 other things across up to ten pages of your site. Free, no signup.
Scan my site