How to fix missing content security policy on Squarespace

Steps for Squarespace

1. Squarespace does not allow custom HTTP response headers.
2. Add a partial CSP via Settings → Advanced → Code Injection → Header field: paste a <meta http-equiv='Content-Security-Policy' content='default-src self; object-src none;'> tag. This only covers HTML pages, not all resource types, and some directives are ignored in meta-tag mode.
3. For stronger enforcement, route your Squarespace site through Cloudflare and add the CSP as a Cloudflare Transform Rule on HTTP responses.

What is missing content security policy?

A Content Security Policy (CSP) is an instruction you send to your visitors' web browsers, embedded in a special HTTP header, that tells the browser exactly which sources of scripts, images, styles, fonts, and other content it is allowed to load on your site. Think of it as a strict guest list at a nightclub door: anything not on the list gets turned away. Without a CSP header, the browser will happily load resources from anywhere — including malicious scripts injected by attackers. Your site currently sends no CSP header at all, which means that protection layer is completely absent.

Without a CSP, your store is significantly more vulnerable to Cross-Site Scripting (XSS) attacks — one of the most common ways attackers steal customer data, hijack sessions, or install payment-skimming code (like Magecart) directly in your shoppers' browsers. A successful XSS attack can expose customers' credit card numbers, passwords, and personal information, leading to chargebacks, fines under GDPR/CCPA, PCI-DSS violations, and severe reputational damage. Google also considers site security as a ranking signal, so a visibly compromised site can lose organic search rankings fast. Adding a CSP is recognized by OWASP as a critical defense-in-depth control against injection attacks (A03:2021).

See the complete Missing content security policy guide for every platform and the full background.