How to fix missing content security policy on BigCommerce

Steps for BigCommerce

1. BigCommerce does not expose arbitrary HTTP response header settings in the merchant admin.
2. The recommended approach is to place BigCommerce behind Cloudflare (free or paid) and configure the CSP as a Cloudflare HTTP Response Headers Transform Rule: Cloudflare Dashboard → your domain → Rules → Transform Rules → Modify Response Headers → Add header → Name: Content-Security-Policy → Value: your policy string.
3. For headless BigCommerce storefronts (Next.js, Gatsby, etc.), set the header in next.config.js (headers() function) or your server middleware.
4. As a partial fallback, add a <meta http-equiv='Content-Security-Policy' content='...'> tag inside your Stencil theme's base.html template (Storefront → My Themes → Edit Theme Files → templates/layout/base.html), understanding that this is weaker than an HTTP header.

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.