Help Ukraine, click for information

CVE-2026-84140

security@mozilla.org
CRITICAL
CVSS Score:9.8/10
Modified
Published: 9/1/2026
Modified: 9/3/2026
4 Affected Products
Risk Assessment
100%
Exploitability
100%
Impact
Overall Risk: 98%
Vulnerability Description

Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

CVSS v3.1 Score
9.8
CRITICAL
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.9
Exploitability
5.9
Impact
Attack Vector Analysis
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

> Thanks for visiting. Stay curious and stay secure. _