Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 128.11.0 |
Related Weaknesses (CWE)
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
- https://www.mozilla.org/security/advisories/mfsa2025-45/
- https://www.mozilla.org/security/advisories/mfsa2025-46/
- https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html
FAQ
What is CVE-2025-5266?
CVE-2025-5266 is a vulnerability with a CVSS score of 4.3 (MEDIUM). 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, Thun...
How severe is CVE-2025-5266?
CVE-2025-5266 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-5266?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox.