Defaults.Exposed › Methodology › v7 registry › CORP (Cross-Origin-Resource-Policy)
CORP (Cross-Origin-Resource-Policy)
Methodology v7 · canonical ID corp-header · Web Security · informational · census as of July 28, 2026
Advanced isolation that hardens against cross-site data leaks.
Definition
| Canonical ID | corp-header |
|---|---|
| Category | Web Security |
| Grade impact | Informational — never moves the grade |
| Pass | The site sends a Cross-Origin-Resource-Policy header. |
| Fail | The header is absent. |
| Example (passing) | Cross-Origin-Resource-Policy: same-origin |
No-data rule: when this check couldn't be determined for a domain (timeout, SERVFAIL, redacted
source) it returns N/A and is excluded from that domain's scoring denominator — "couldn't determine"
is never counted as a failure. "Determined absent" is a real fail.
Prevalence across the census
0.89% of graded domains send a Cross-Origin-Resource-Policy header (2,449,105 of 275,666,275, as of July 28, 2026).
Header presence measured from raw HTTP headers, scaled to the deduped graded denominator; the three cross-origin measures overlap.
Census denominator: 275,666,275 graded domains. Aggregates only — never an individual domain's result.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: defaults.exposed/en/fix/cross-origin-headers
Cite this check
Defaults.Exposed, "CORP (Cross-Origin-Resource-Policy) (corp-header)", Grading Methodology v7 (census as of July 28, 2026). https://defaults.exposed/methodology/v7/corp-header
Permalink: https://defaults.exposed/methodology/v7/corp-header ·
All 34 checks: v7 registry ·
Machine-readable: checks.json ·
Licence: open data