Mozilla Firefox Security Updates – 17 June 2026

The addressed vulnerabilities could allow the attacker to conduct denial-of-service and spoofing attacks, gain elevated privilege, trigger memory corruption, obtain sensitive information, bypass security restrictions, and execute arbitrary code on the affected systems.

Sample of the addressed vulnerabilities:

1) Mozilla Firefox Same-Origin Policy Bypass in the Networking: Cookies Component Vulnerability (CVE-2026-12304):

• CVSS: 9.1
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Consequences: Bypass Security

2) Mozilla Firefox Privilege Escalation in the Graphics: WebRender Component (CVE-2026-12289):

• CVSS: 8.8
• Attack Vector: Network
• Attack Complexity: Low Firefox
• Privileges Required: None
• User Interaction: Required
• Consequences: Gain Privileges