How to fix insecure cookie on Squarespace

Steps for Squarespace

1. Squarespace-managed session and CSRF cookies are set by Squarespace's infrastructure. Ensure HTTPS is enabled: Settings → Advanced → SSL and set to 'Secure' (HTTPS only) with 'HSTS' toggled on.
2. Squarespace does not expose server-side cookie configuration to store owners for platform cookies — if a Squarespace-native cookie is missing flags, report it via Squarespace Help → Contact Support.
3. For cookies set via custom Code Injection (Settings → Advanced → Code Injection) or page Header/Footer code blocks: audit any `document.cookie` writes; append `; Secure; SameSite=Strict` to each. Note: HttpOnly cannot be set via client-side JS — remove sensitive cookie logic from injected scripts entirely.
4. For cookies introduced by third-party extensions or connected services (e.g., Mailchimp popup, live chat): update the integration and check the vendor's documentation for cookie-security options.

Set-Cookie: CSRFTOKEN=abc123; Path=/; Secure; HttpOnly; SameSite=Strict

What is insecure cookie?

Every time a visitor lands on your store, their browser receives small data files called cookies — one of which typically holds their login session or a CSRF token (a secret code that proves form submissions came from your real site, not an attacker). Each cookie can carry protective "flags" that tell the browser how to handle it safely. The three critical flags are: **HttpOnly** (JavaScript running on the page cannot read the cookie, so a hacked ad script cannot steal it), **Secure** (the browser only sends the cookie over HTTPS, never plain HTTP), and **SameSite=Strict** (the browser refuses to send the cookie when a request originates from a third-party site, blocking cross-site request forgery attacks). When any of these flags are missing, the cookie is left partially unprotected.

A missing HttpOnly flag is the primary enabler of session-hijacking via Cross-Site Scripting (XSS): if even one ad, chat widget, or third-party script on your page is ever compromised, it can silently read your customers' session cookies and hand them to an attacker, who then logs in as that customer and sees their orders, saved addresses, and payment methods. A missing Secure flag risks cookies being transmitted in plain text if a customer ever hits an HTTP link, exposing their session to network eavesdroppers (especially on public Wi-Fi). A missing SameSite flag enables Cross-Site Request Forgery (CSRF), where a malicious page tricks a logged-in customer's browser into submitting unwanted actions — like changing their email or placing a fraudulent order — on your store. Beyond customer harm, a breach involving stolen session tokens can trigger PCI-DSS violations, GDPR fines, and lasting reputational damage that directly kills revenue.

See the complete Insecure cookie guide for every platform and the full background.