Improper isolation or compartmentalization in Mozilla products - CVE-2026-117959
Published: October 27, 2026
Vulnerability identifier: #VU158171
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-2026-117959
CWE-ID: CWE-653
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to weaken site isolation and potentially access information across site boundaries.
The vulnerability exists due to insufficient compartmentalization in the DOM: Service Workers component when handling service worker activity. A remote attacker can supply crafted content to undermine separation between sites and potentially access otherwise isolated information.
Affected software
Firefox ESR
Mozilla Firefox
Firefox for Android
Mozilla Firefox
Firefox for Android
How to mitigate CVE-2026-117959
Install security update from vendor's website.
Firefox ESR - update to 153.6.0
Firefox for Android - update to 159.0
Mozilla Firefox - update to 159.0
Firefox for Android - update to 159.0
Mozilla Firefox - update to 159.0