CVE-2025-5266
Last modified
CVE-2025-5266 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.. EPSS estimates a 0.26% chance of exploitation in the next 30 days.
Description
Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 128.11.0 |
| Mozilla | Firefox | < 139.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1965628Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-42/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-44/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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