Mozilla Firefox Security Updates – 21 May 2026

The addressed vulnerabilities could allow the remote attacker to conduct denial-of- service and spoofing attacks, obtain sensitive information, bypass security restrictions, gain elevated privileges, execute arbitrary code, and gain access to the affected system.

Sample of the addressed vulnerabilities:

1. Mozilla Firefox Sandbox Escape in the Profile Backup Component Vulnerability (CVE-2026-8401):

• CVSS: 9.8
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Consequences: Bypass Security

2. Mozilla Firefox Privilege Escalation in the Security Component Vulnerability (CVE-2026-8970):

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