CVE-2026-16396
High
Description
Privilege escalation in WebExtensions. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.
SeverityHigh
CVSS8.8
Exploit probability—
Product
Mozilla Firefox
PublishedJul 21, 2026
First seenJul 21, 2026
Weakness typeCWE-269Improper privilege management
How to fix
Update
- mozilla firefox140.13.0, 153.0.0 or later
- mozilla thunderbird140.13.0, 153.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mozilla firefox | v < 140.13.0, v < 153.0.0 | 140.13.0, 153.0.0 |
| mozilla thunderbird | v < 140.13.0, 141.0 ≤ v < 153.0 | 140.13.0, 153.0 |
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