CVE-2026-100788: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 0.4% chance of exploitation in the next 30 days.

Invalid pointer in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

Affected products

• Mozilla Firefox
• Mozilla Thunderbird

Published 2026-09-29. Last modified 2026-10-01.