Protection mechanism failure in Mozilla products - CVE-2026-117966
Published: October 27, 2026
Vulnerability identifier: #VU158133
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-2026-117966
CWE-ID: CWE-693
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to undermine site isolation and potentially access information across site boundaries.
The vulnerability exists due to improper enforcement of site-isolation boundaries in the HTTP networking component when processing network-related content. A remote attacker can supply crafted content to interfere with site separation and potentially access information that should remain isolated.
Affected software
Mozilla Firefox
Firefox ESR
Firefox for Android
Firefox ESR
Firefox for Android
How to mitigate CVE-2026-117966
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