Origin validation error in Mozilla products - CVE-2026-117912
Published: October 27, 2026
Vulnerability identifier: #VU158100
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-117912
CWE-ID: CWE-346
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass the same-origin policy and potentially access information across origin boundaries.
The vulnerability exists due to improper enforcement of the same-origin policy in the CSS parsing and computation component when processing styles involving different origins. A remote attacker can supply crafted style content to bypass origin restrictions and potentially obtain information that should be isolated.
Affected software
Mozilla Firefox
Firefox ESR
Firefox for Android
Firefox ESR
Firefox for Android
How to mitigate CVE-2026-117912
Install security update from vendor's website.
Mozilla Firefox - update to 159.0
Firefox for Android - update to 159.0
Firefox ESR - addressed in versions 115.44.0, 153.6.0
Firefox for Android - update to 159.0
Firefox ESR - addressed in versions 115.44.0, 153.6.0