CVE-2026-74934
High
Description
Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
SeverityHigh
CVSS7.5
Exploit probability—
Product
Mozilla Firefox
PublishedAug 18, 2026
First seenAug 18, 2026
How to fix
Update
- mozilla firefox115.39.0, 140.14.0, 153.1.0 or later
- mozilla thunderbird140.14.0, 153.1.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mozilla firefox | v < 115.39.0, 116.0 ≤ v < 140.14.0, 141.0 ≤ v < 153.1.0 | 115.39.0, 140.14.0, 153.1.0 |
| mozilla thunderbird | v < 140.14.0, 141.0 ≤ v < 153.1.0 | 140.14.0, 153.1.0 |
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