CVE-2020-12391: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

Documents formed using data: URLs in an OBJECT element failed to inherit the CSP of the creating context. This allowed the execution of scripts that should have been blocked, albeit with a unique opaque origin. This vulnerability affects Firefox < 76.

Affected products

• Mozilla Firefox: before 76.0 (fixed in 76.0)

Published 2020-05-26. Last modified 2026-06-17.