VDB
CVE-2026-74986
CVE-2026-74986
PUBLISHED
CVSS 9.1 CRITICAL
Reported by mozilla · Published August 18, 2026
Site isolation issue in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
Risk Scores
CVSS 3.1
9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | 153.1, 154 |
| Mozilla | Thunderbird | 153.1, 154 |
| Mozilla | Thunderbird | 153.1, 154, 153.1 |
| Mozilla | Firefox | 153.1, 154, 153.1 |
Timeline
- Aug 18, 2026 Coalition ESS Score
- Aug 18, 2026 CVE Published
- Aug 20, 2026 CVE Updated
- Aug 24, 2026 EPSS Score
- Aug 26, 2026 EPSS Score
- Aug 30, 2026 EPSS Score
- Sep 4, 2026 EPSS Score
- Sep 5, 2026 Security Advisory
- Sep 9, 2026 EPSS Score
- Sep 15, 2026 EPSS Score
- Sep 16, 2026 EPSS Score
- Sep 18, 2026 EPSS Score