security fix workflow

How to fix a missing CSP header

Add a Content Security Policy without breaking scripts, styles, analytics, or checkout flows.

What this issue means

A missing CSP means the browser has fewer rules limiting where scripts, styles, images, and frames can load from.

Why it matters

CSP helps reduce XSS impact, but a rushed policy can break real product flows.

Evidence to collect

Use the linked CheckWebs diagnostic first, apply the fix, then retest the same URL to confirm the signal changed.

Start with the same URL in the linked CheckWebs tool, save the failing signal, apply the fix, then retest the final redirected URL. Avoid judging the fix from a cached screenshot or a different URL variant.

How to check it

1Run Security Headers Grade.
2Inventory current script, style, image, frame, connect, and font sources.
3Generate a starter policy and test in report-only mode.

How to fix it

1Start with Content-Security-Policy-Report-Only.
2Whitelist only sources your site actually needs.
3Move to enforcement after monitoring violations.

Platform-specific fixes

Next.js

Set CSP headers at the edge or in next.config headers.
Account for inline scripts, analytics, and nonce strategy.

Cloudflare

Deploy CSP through response header rules.
Use report-only during rollout.

Nginx

Add Content-Security-Policy-Report-Only first.
Promote to Content-Security-Policy after violations are understood.

Validate the fix

1Re-run Security Headers Grade.
2Check browser console and CSP reports.

FAQ

Can CSP break my website?+

Yes. That is why report-only rollout and source inventory are important before enforcement.

Loading CheckWebs…

security fix workflow

How to fix a missing CSP header

Add a Content Security Policy without breaking scripts, styles, analytics, or checkout flows.

What this issue means

A missing CSP means the browser has fewer rules limiting where scripts, styles, images, and frames can load from.

Why it matters

CSP helps reduce XSS impact, but a rushed policy can break real product flows.

Evidence to collect

Use the linked CheckWebs diagnostic first, apply the fix, then retest the same URL to confirm the signal changed.

How to check it

1Run Security Headers Grade.
2Inventory current script, style, image, frame, connect, and font sources.
3Generate a starter policy and test in report-only mode.

How to fix it

1Start with Content-Security-Policy-Report-Only.
2Whitelist only sources your site actually needs.
3Move to enforcement after monitoring violations.

Platform-specific fixes

Next.js

Set CSP headers at the edge or in next.config headers.
Account for inline scripts, analytics, and nonce strategy.

Cloudflare

Deploy CSP through response header rules.
Use report-only during rollout.

Nginx

Add Content-Security-Policy-Report-Only first.
Promote to Content-Security-Policy after violations are understood.

Validate the fix

1Re-run Security Headers Grade.
2Check browser console and CSP reports.

FAQ

Can CSP break my website?+

Yes. That is why report-only rollout and source inventory are important before enforcement.