CVE-2025-5266

MEDIUM

Firefox < 128.11.0, 128.11-128.*, < 139.0, >=139 Sensitive Info Exposure via Cross-Origin Script Load Events

Title source: llm

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.

References (7)

Core 7

Core References

Mailing List

https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html

Mailing List

https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html

Permissions Required

https://bugzilla.mozilla.org/show_bug.cgi?id=1965628

Vendor Advisory

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/

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2025-46/

Scores

CVSS v3 4.3

EPSS 0.0043

EPSS Percentile 63.0%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-200

Status published

Products (6)

mozilla/firefox < 128.11.0

mozilla/firefox < 139.0

Mozilla/Firefox 128.11 - 128.*

Mozilla/Firefox 139

Mozilla/Thunderbird 128.11 - 128.*

Mozilla/Thunderbird 139

Published May 27, 2025

Tracked Since Feb 18, 2026