CVE-2026-74981: Mozilla Firefox

High severity, CVSS 8.1. EPSS: 0.2% chance of exploitation in the next 30 days.

Site isolation issue in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

Affected products

• Mozilla Firefox: before 153.1.0 (fixed in 153.1.0)
• Mozilla Thunderbird: before 153.1.0 (fixed in 153.1.0)

Published 2026-08-18. Last modified 2026-08-25.