Strict-Transport-Security is missing includeSubDomains
HTTPS is enforced for this hostname but not for its subdomains.
Why it matters
HTTPS is enforced for this hostname but not for its subdomains. That leaves a gap: an attacker who can intercept traffic can direct a victim to a subdomain over plain HTTP, and because HSTS does not cover it, the browser will not upgrade the connection. Cookies scoped to the parent domain can then be exposed on that subdomain.
How ShipReady detects it
Shared tables and rules for the two halves below. Split because this check was a hybrid: nine rules read the headers of a response we already have, which genuinely differ between routes, while missing-https-redirect probes the http:// equivalent of the origin — one fact, and running it per page would issue the same request ten times.
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 1.3.0.
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.
Your Strict-Transport-Security header protects this hostname but not its subdomains. Add the includeSubDomains directive (for example `Strict-Transport-Security: max-age=63072000; includeSubDomains`). Before you do, confirm every subdomain — including internal tools and staging hosts — can serve HTTPS, because the directive forces HTTPS on all of them and browsers cache it for the full max-age.
Frequently asked questions
- What does "Strict-Transport-Security is missing includeSubDomains" mean?
- HTTPS is enforced for this hostname but not for its subdomains.
- How serious is it?
- ShipReady rates this low. Worth fixing. Small individually, and they accumulate.
- 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.
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