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Mozilla Firefox and Thunderbird Same-Origin Policy Bypass Vulnerability

Vulnerability

A same-origin policy bypass vulnerability has been identified in the Networking: JAR component, affecting multiple versions of Firefox and Thunderbird. Specifically, this vulnerability impacts Firefox versions prior to 148, Firefox ESR versions prior to 140.8, Thunderbird versions prior to 148, and Thunderbird ESR versions prior to 140.8.

Impact

Exploitation of this vulnerability allows for a same-origin policy bypass, which could lead to cross-origin resource sharing issues or unauthorized access to resources from different origins.

Remediation

Users can upgrade to Firefox 148, Firefox ESR 140.8, Thunderbird 148, or Thunderbird ESR 140.8 to address this vulnerability.

Added: Feb 24, 2026, 2:38 PM
Updated: Feb 24, 2026, 10:39 PM

Vulnerability Rating

Custom Algorithm
spread
8.4
impact
1.3
exploitability
4.2
remediation
7.7
relevance
3.1
threat
0.0
urgency
2.9
incentive
0.0

Our algorithm analyzes dozens of metrics to generate these 8 key vulnerability categories, which are then combined to calculate the overall risk score.