CVE-2026-84128
published 2026-09-01CVE-2026-84128: Privilege escalation in the WebDriver BiDi component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
PriorityP347high8.8CVSS 3.1
AVNACLPRNUIRSUCHIHAH
EPSS
0.44%
36.1th percentile
Privilege escalation in the WebDriver BiDi component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
Affected
4 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 155 | Firefox 155 |
| mozilla | firefox | < 155.0.0 | 155.0.0 |
| mozilla | thunderbird | < Thunderbird 155 | Thunderbird 155 |
| mozilla | thunderbird | < 155.0 | 155.0 |
CVSS provenance
nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vendor_redhat8.8HIGH
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Red Hat
firefox: thunderbird: Privilege escalation in the WebDriver BiDi component
vendor_redhat·2026-09-01·CVSS 8.8
CVE-2026-84128 [HIGH] CWE-266 firefox: thunderbird: Privilege escalation in the WebDriver BiDi component
firefox: thunderbird: Privilege escalation in the WebDriver BiDi component
Privilege escalation in the WebDriver BiDi component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Privilege escalation in the WebDriver BiDi component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: firefox (Red Hat Enterprise Linux 10) - Not affected
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Not affected
Package: rhel10/thunderbird-flatpak (Red Hat Enterprise Linux 10) - Not affected
Package: thunderbird (Red Hat Enterprise Linux 10) - Not affected
Package: fire
Mozilla
Mozilla Foundation Security Advisory 2026-82: CVE-2026-84128
vendor_mozilla·CVSS 8.8
CVE-2026-84128 [HIGH] Mozilla Foundation Security Advisory 2026-82: CVE-2026-84128
Mozilla Foundation Security Advisory 2026-82
CVE: CVE-2026-84128
Product: Firefox
Impact: high
Fixed in: Firefox 155
Mozilla
Mozilla Foundation Security Advisory 2026-86: CVE-2026-84128
vendor_mozilla·CVSS 8.8
CVE-2026-84128 [HIGH] Mozilla Foundation Security Advisory 2026-86: CVE-2026-84128
Mozilla Foundation Security Advisory 2026-86
CVE: CVE-2026-84128
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 155
VulDB
Mozilla Firefox up to 154 WebDriver BiDi privileges management (Nessus ID 342308)
vuldb·2026-09-03·CVSS 8.8
CVE-2026-84128 [HIGH] Mozilla Firefox up to 154 WebDriver BiDi privileges management (Nessus ID 342308)
A vulnerability was found in Mozilla Firefox up to 154. It has been declared as critical. Affected by this vulnerability is an unknown functionality of the component WebDriver BiDi. Executing a manipulation can lead to improper privilege management.
This vulnerability is handled as CVE-2026-84128. The attack can be executed remotely. There is not any exploit available.
It is recommended to upgrade the affected component.
GHSA
Privilege escalation in the WebDriver BiDi component.
ghsa_unreviewed·2026-09-01
CVE-2026-84128 [HIGH] CWE-284 Privilege escalation in the WebDriver BiDi component.
Privilege escalation in the WebDriver BiDi component. This vulnerability was fixed in Firefox 155.
No detection rules found.
No public exploits indexed.
2026-09-01
Published