CVE-2025-5266 — Sensitive Information Exposure in Mozilla Firefox

CWE-200 — Sensitive Information ExposureCWE-829 — Inclusion of Functionality from Untrusted Control Sphere11 documents8 sources
Severity
4.3MEDIUMNVD
EPSS
0.4%
top 37.11%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla ThunderbirdMozilla Firefox
Timeline
PublishedMay 27
Latest updateJul 22

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 vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:NExploitability: 2.8 | Impact: 1.4

Affected Packages2 packages

▶NVDmozilla/firefox< 128.11.0+1
▶Debianmozilla/thunderbird< 1:128.11.0esr-1~deb11u1+3

🔴Vulnerability Details

3
OSV
CVE-2025-5266: Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks↗2025-05-27
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GHSA
GHSA-xv7q-j96c-5r6v: Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks↗2025-05-27
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CVEList
Script element events leaked cross-origin resource status↗2025-05-27
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📋Vendor Advisories

7
Ubuntu
Thunderbird vulnerabilities↗2025-07-22
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Red Hat
firefox: thunderbird: Script element events leaked cross-origin resource status↗2025-05-27
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Debian
CVE-2025-5266: firefox - Script elements loading cross-origin resources generated load and error events w...↗2025
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Mozilla
Mozilla Foundation Security Advisory 2025-44: CVE-2025-5266↗
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Mozilla
Mozilla Foundation Security Advisory 2025-42: CVE-2025-5266↗
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CVE-2025-5266 — Sensitive Information Exposure | cvebase