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CORS and Content-Security-Policy: complementary browser controls
CORS governs reading cross-origin responses; CSP reduces XSS blast radius and restricts where scripts and connections may load from.
1 min read
corscspsecurity
Why both layers matter
CSP can block inline script injection and limit connect-src destinations for fetch/XHR/WebSocket in modern browsers.
Misconfigured CSP can break legitimate API calls while CORS still passes—test policy changes in a staging environment.
connect-src and allowlists
Align connect-src with your API domains and proxy endpoints; avoid overly broad wildcards in production.
Use report-uri or report-to for CSP monitoring without blocking traffic during rollout.