performing-content-security-policy-bypass

First analyze the policy for weak directives like unsafe-inline or unsafe-eval, then check whitelisted domains for JSONP endpoints or AngularJS libraries that allow callback or template injection. Confirm the bypass only when a script actually executes in the browser under the enforced policy.

Inspect response headers for Content-Security-Policy versus Content-Security-Policy-Report-Only. Report-only mode logs violations without blocking, so plain XSS works directly and should not be reported as a CSP bypass.

The workflow uses Burp Suite for intercepting responses and analyzing headers, Google CSP Evaluator for automated policy analysis, and browser developer tools for monitoring CSP violation reports during testing.

Yes, through nonce leakage via CSS attribute selector brute-forcing, nonce reuse across pages, or DOM clobbering. Note that unsafe-inline is ignored when a nonce or strict-dynamic is present, so focus shifts to leaking the nonce value.

Under CSP3, browsers ignore unsafe-inline whenever a nonce or hash source is present in script-src. Inline injection attempts will be blocked, so testing must pivot to nonce leakage, script gadgets, or whitelisted-domain abuse.

A weak-looking policy is only a lead, not a finding; a bypass is confirmed only when execution or exfiltration occurs under the enforced policy. Well-formed nonce-based policies with strict-dynamic and no whitelisted CDNs may leave no viable bypass path.