Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability affects Firefox < 139 and Firefox ESR < 128.11.
CVE ID: CVE-2025-5266
CVSS Base Severity: MEDIUM
CVSS Base Score: 6.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Vendor: Mozilla
Product: Firefox, Firefox ESR
EPSS Score: 0.08% (probability of being exploited)
EPSS Percentile: 23.45% (scored less or equal to compared to others)
EPSS Date: 2025-06-18 (when was this score calculated)