Origin validation error in Mozilla products - CVE-2026-84137
Published: September 1, 2026
Vulnerability identifier: #VU146621
CSH Severity: Low
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-84137
CWE-ID: CWE-346
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to spoof content.
The vulnerability exists due to improper origin validation in the DOM: Core & HTML component when rendering crafted web content. A remote attacker can present crafted content to spoof content.
User interaction is required to visit a crafted website or URL.
Affected software
Firefox for Android
Mozilla Firefox
Firefox ESR
Mozilla Firefox
Firefox ESR
How to mitigate CVE-2026-84137
Install security update from vendor's website.
Firefox for Android - update to 155.0
Mozilla Firefox - update to 155.0
Firefox ESR - update to 153.2.0
Mozilla Firefox - update to 155.0
Firefox ESR - update to 153.2.0