How to fix hsts max age too short on Adobe Commerce (Magento)

Steps for Adobe Commerce (Magento)

1. In the Magento Admin, navigate to Stores → Configuration → General → Web → Base URLs (Secure) and ensure 'Use Secure URLs on Storefront' and 'Use Secure URLs in Admin' are both set to Yes.
2. HSTS itself must be set at the web server or Varnish/FastCGI layer, not inside Magento's admin UI.
3. For Nginx, add inside your HTTPS server {} block: add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
4. For Apache, add to the VirtualHost or .htaccess: Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
5. For Adobe Commerce Cloud (Magento Cloud), add the header in your .magento.app.yaml or via the Fastly service configuration in the Cloud Console under CDN → Headers.
6. Clear Magento's full-page cache after the change: Admin → System → Cache Management → Flush Magento Cache. Verify headers with DevTools or curl -I https://yourdomain.com.

What is hsts max age too short?

HTTP Strict Transport Security (HSTS) is a security header your web server sends to browsers that says: "Only ever connect to this site over HTTPS — never plain HTTP." The `max-age` value inside that header tells the browser how many seconds to remember and enforce that rule. A value of 86400 means just one day — after 24 hours the browser forgets the instruction and could allow an unencrypted HTTP connection again. The industry standard is 31536000 (one full year), meaning the browser stays protected for 365 days after each visit.

A short max-age creates a real window of vulnerability every single day. If a visitor's browser cache expires and they visit your store over an insecure network (coffee shop Wi-Fi, hotel hotspot), an attacker can intercept that initial unencrypted HTTP request and steal login credentials, session cookies, or payment data — a classic SSL-stripping attack. Beyond security, Google has used HTTPS as a ranking signal since 2014 and continues to favor sites that implement it properly; a misconfigured HSTS header signals to security-aware crawlers and auditors that your HTTPS setup is incomplete. Short max-age values are also explicitly flagged by OWASP and browser preload-list requirements, and many enterprise buyers and compliance frameworks (PCI-DSS, SOC 2) require HSTS to be set correctly before approving a vendor.

See the complete Hsts max age too short guide for every platform and the full background.