CVE-2026-84140
published 2026-09-01CVE-2026-84140: 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.
PriorityP353critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.18%
7.9th percentile
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.
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 155 | Firefox 155 |
| mozilla | firefox | < 153.2.0 | 153.2.0 |
| mozilla | firefox | >= 154.0.0 < 155.0.0 | 155.0.0 |
| mozilla | firefox_esr | < Firefox ESR 153.2 | Firefox ESR 153.2 |
| mozilla | thunderbird | < Thunderbird 155 | Thunderbird 155 |
| mozilla | thunderbird | < Thunderbird 153.2 | Thunderbird 153.2 |
| mozilla | thunderbird | < 153.2.0 | 153.2.0 |
| mozilla | thunderbird | >= 154.0 < 155.0 | 155.0 |
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Mozilla
Mozilla Foundation Security Advisory 2026-86: CVE-2026-84140
vendor_mozilla
CVE-2026-84140 Mozilla Foundation Security Advisory 2026-86: CVE-2026-84140
Mozilla Foundation Security Advisory 2026-86
CVE: CVE-2026-84140
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 155
Mozilla
Mozilla Foundation Security Advisory 2026-88: CVE-2026-84140
vendor_mozilla
CVE-2026-84140 Mozilla Foundation Security Advisory 2026-88: CVE-2026-84140
Mozilla Foundation Security Advisory 2026-88
CVE: CVE-2026-84140
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 153.2
Mozilla
Mozilla Foundation Security Advisory 2026-82: CVE-2026-84140
vendor_mozilla
CVE-2026-84140 Mozilla Foundation Security Advisory 2026-82: CVE-2026-84140
Mozilla Foundation Security Advisory 2026-82
CVE: CVE-2026-84140
Product: Firefox
Impact: high
Fixed in: Firefox 155
Mozilla
Mozilla Foundation Security Advisory 2026-85: CVE-2026-84140
vendor_mozilla
CVE-2026-84140 Mozilla Foundation Security Advisory 2026-85: CVE-2026-84140
Mozilla Foundation Security Advisory 2026-85
CVE: CVE-2026-84140
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 153.2
VulDB
Mozilla Firefox up to 153.1/154 Navigation isolation (Nessus ID 342307)
vuldb·2026-09-03
CVE-2026-84140 [CRITICAL] Mozilla Firefox up to 153.1/154 Navigation isolation (Nessus ID 342307)
A vulnerability classified as critical was found in Mozilla Firefox up to 153.1/154. Affected by this vulnerability is an unknown functionality of the component Navigation Component. Such manipulation leads to improper isolation or compartmentalization.
This vulnerability is listed as CVE-2026-84140. The attack may be performed from remote. There is no available exploit.
Upgrading the affected component is advised.
GHSA
Site isolation issue in the DOM: Navigation component.
ghsa_unreviewed·2026-09-01
CVE-2026-84140 Site isolation issue in the DOM: Navigation component.
Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 155 and Firefox ESR 153.2.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-09-01
Published