CVE-2026-84129

critical · 9.8

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.

9.8

CVSS

0.2%

EPSS (exploit prob.)

8th

EPSS percentile

2026-09-01

Published

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

CWE-346

Affected products

Vendor	Product	Affected versions
mozilla	firefox	< 153.2.0
mozilla	firefox	>= 154.0.0, < 155.0.0
mozilla	thunderbird	< 153.2.0
mozilla	thunderbird	>= 154.0, < 155.0

Check a specific version with /api/v1/cve/match.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2055028
https://www.mozilla.org/security/advisories/mfsa2026-82/
https://www.mozilla.org/security/advisories/mfsa2026-85/
https://www.mozilla.org/security/advisories/mfsa2026-86/
https://www.mozilla.org/security/advisories/mfsa2026-88/

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-84129