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CVE

CVE-2025-5266

Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leak

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.

MEDIUM · CVSS 4.3 EPSS 0.00434
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules1 YARA rules0
⬡

Weakness Classification

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
▤

Affected Products & Versions

2
mozilla firefox< 128.11.0
mozilla firefox< 139.0
◈

Sigma Hunt Rules

1
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSQLite Firefox Profile Data DB Access
▣

Scoring & Timeline

4.3
MEDIUM · CVSS v3.1 · security@mozilla.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD27 May 2025 · 01:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

30
suse-csafopenSUSE-SU-2025:20135-1
suse-csafSUSE-SU-2025:21170-1
usnUSN-7663-1
suse-csafopenSUSE-SU-2025:15315-1
suse-csafSUSE-SU-2025:01946-1
🔗

References & Sources

7
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
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
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