Mozilla security advisory (AV26-840)
Brief
Serial Number: AV26-840
Date: August 21, 2026
As of August 18, 2026, Mozilla is affected by vulnerabilities in the following products:
- Firefox
- versions prior to 154
- Firefox ESR
- versions prior to 115.39
- versions prior to 140.14
- versions prior to 153.1
- Thunderbird
- versions prior to 140.14
- versions prior to 153.1
- versions prior to 154
The Cyber Centre encourages users and administrators to review the provided web link and apply any necessary updates as they become available.
- Mozilla Foundation Security Advisories — Mozilla
Mozilla security advisory (AV26-840) - Canadian Centre for Cyber Security