CVE-2026-100787
Critical
Description
Sandbox escape in the XUL component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.
SeverityCritical
CVSS9.6
Exploit probability—
Product
Mozilla Firefox
PublishedSep 29, 2026
First seenSep 29, 2026
Weakness typeCWE-20Improper input validation
How to fix
Update
- mozilla firefox153.4.0, 157.0.0 or later
- mozilla thunderbird153.4.0, 157.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mozilla firefox | v < 153.4.0, 154.0.0 ≤ v < 157.0.0 | 153.4.0, 157.0.0 |
| mozilla thunderbird | v < 153.4.0, 154.0 ≤ v < 157.0 | 153.4.0, 157.0 |
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