CVE-2026-100821
Site isolation issue in the Panning and Zooming component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
- Published Sep 29, 2026
- CVSS 4.7 medium
- 0.2% chance of exploitation in the next 30 days (EPSS)
- A fix is available