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CVE-2019-9803
HIGH · CVSS 7.4
EPSS exploitation probability: 0%
Published 2019-04-26T17:29:03.257 · Last modified 2026-06-17T02:44:29.140

Summary

The Upgrade-Insecure-Requests (UIR) specification states that if UIR is enabled through Content Security Policy (CSP), navigation to a same-origin URL must be upgraded to HTTPS. Firefox will incorrectly navigate to an HTTP URL rather than perform the security upgrade requested by the CSP in some circumstances, allowing for potential man-in-the-middle attacks on the linked resources. This vulnerability affects Firefox < 66.

Affected products

mozilla — firefox

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.