CVE-2026-84133
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
Site isolation issue in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
Risk Assessment
May allow a website to access data from another site, breaking security isolation.
Recommendation
Update Firefox or Thunderbird to the latest available version containing the fix.
Other vulnerabilities in Firefox
See all- CVE-2026-84141Critical
Integer overflow in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
- CVE-2026-84140Critical
Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
- CVE-2026-84134Critical
Other issue in the Profile Backup component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
- CVE-2026-84129Critical
The vulnerability concerns a site isolation issue in the DOM: Navigation component in Firefox and Thunderbird. The flaw was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
- CVE-2026-84121Critical
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.
- CVE-2026-84119Critical
Sandbox escape vulnerability due to use-after-free in the DOM: Navigation component. 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.
- CVE-2026-75874Critical
Sandbox escape in the Remote Settings Client component. Fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.
- CVE-2026-74986Critical
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.
- CVE-2026-74985Critical
Privilege escalation in the Enterprise Policies component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
- CVE-2026-74979Critical
Mitigation bypass in the Add-ons Manager component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
Original NVD description (English source)
Site isolation issue in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.