CVE-2025-5266

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 3.1

4.3CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 27% of CVEs (scores of 2026-10-25)

CWE

CWE-200

Published

2025-05-27

Modified

2026-10-05

Record from

the NVD, synced 2026-10-19

Affected

• mozilla:firefox

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1965628
• https://www.mozilla.org/security/advisories/mfsa2025-42/
• https://www.mozilla.org/security/advisories/mfsa2025-44/
• https://www.mozilla.org/security/advisories/mfsa2025-45/
• https://www.mozilla.org/security/advisories/mfsa2025-46/

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