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Vol. 1 · Ed. 2026
CyberGlossary
Entry № 262

Cross-Origin Embedder Policy (COEP)

¿Qué es Cross-Origin Embedder Policy (COEP)?

Cross-Origin Embedder Policy (COEP)An HTTP response header that forces every cross-origin subresource a document loads to explicitly opt in via CORS or CORP, completing the cross-origin isolation prerequisites alongside COOP.


Cross-Origin Embedder Policy (`Cross-Origin-Embedder-Policy`) is a browser security header that controls whether a document is allowed to embed cross-origin subresources without an explicit opt-in. With `require-corp`, every image, script, iframe, font, or other cross-origin asset must carry either a CORS response (`Access-Control-Allow-Origin`) or a Cross-Origin-Resource-Policy (CORP) header that authorizes the embed; otherwise the load fails. With `credentialless`, cross-origin requests for no-CORS resources are sent without cookies and treated as anonymous. COEP exists primarily to enable cross-origin isolation: when paired with `Cross-Origin-Opener-Policy: same-origin`, it unlocks high-resolution timers, `SharedArrayBuffer`, and other features that were restricted to mitigate Spectre. Deploying COEP often requires auditing third-party assets to ensure they ship `Cross-Origin-Resource-Policy: cross-origin` or proper CORS.

Ejemplos

  1. 01

    A WebAssembly-heavy app sends `Cross-Origin-Embedder-Policy: require-corp` and `Cross-Origin-Opener-Policy: same-origin` to re-enable `SharedArrayBuffer`.

  2. 02

    A CDN that serves third-party scripts adds `Cross-Origin-Resource-Policy: cross-origin` so its assets remain embeddable in COEP-enforcing pages.

Preguntas frecuentes

¿Qué es Cross-Origin Embedder Policy (COEP)?

An HTTP response header that forces every cross-origin subresource a document loads to explicitly opt in via CORS or CORP, completing the cross-origin isolation prerequisites alongside COOP. Pertenece a la categoría de Seguridad de aplicaciones en ciberseguridad.

¿Qué significa Cross-Origin Embedder Policy (COEP)?

An HTTP response header that forces every cross-origin subresource a document loads to explicitly opt in via CORS or CORP, completing the cross-origin isolation prerequisites alongside COOP.

¿Cómo funciona Cross-Origin Embedder Policy (COEP)?

Cross-Origin Embedder Policy (`Cross-Origin-Embedder-Policy`) is a browser security header that controls whether a document is allowed to embed cross-origin subresources without an explicit opt-in. With `require-corp`, every image, script, iframe, font, or other cross-origin asset must carry either a CORS response (`Access-Control-Allow-Origin`) or a Cross-Origin-Resource-Policy (CORP) header that authorizes the embed; otherwise the load fails. With `credentialless`, cross-origin requests for no-CORS resources are sent without cookies and treated as anonymous. COEP exists primarily to enable cross-origin isolation: when paired with `Cross-Origin-Opener-Policy: same-origin`, it unlocks high-resolution timers, `SharedArrayBuffer`, and other features that were restricted to mitigate Spectre. Deploying COEP often requires auditing third-party assets to ensure they ship `Cross-Origin-Resource-Policy: cross-origin` or proper CORS.

¿Cómo defenderse de Cross-Origin Embedder Policy (COEP)?

Las defensas contra Cross-Origin Embedder Policy (COEP) combinan habitualmente controles técnicos y prácticas operativas, como se detalla en la definición.

¿Cuáles son otros nombres para Cross-Origin Embedder Policy (COEP)?

Nombres alternativos comunes: COEP.

Términos relacionados

Véase también