CVE-2026-100781
Critical
Description
Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender 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.
SeverityCritical
CVSS9.6
Exploit probability—
Product
Mozilla Firefox
PublishedSep 29, 2026
First seenSep 29, 2026
Weakness typeCWE-119Memory buffer bounds error
How to fix
Update
- mozilla firefox157.0.0, 115.42.0, 140.17.0, 153.4.0 or later
- mozilla thunderbird157.0, 140.17.0, 153.4.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mozilla firefox | v < 157.0.0, 115.1.0 ≤ v < 115.42.0, 140.0 ≤ v < 140.17.0, 153.0 ≤ v < 153.4.0 | 157.0.0, 115.42.0, 140.17.0, 153.4.0 |
| mozilla thunderbird | v < 157.0, 140.0 ≤ v < 140.17.0, 153.0 ≤ v < 153.4.0 | 157.0, 140.17.0, 153.4.0 |
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