CVE-2026-84121
Critical · 9.6CVSS
9.6
EPSS
0.3%
Published
Sep 1, 2026
CISA due date
—
The record
Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|
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