Improper isolation or compartmentalization in Mozilla products - CVE-2026-117958
Published: October 27, 2026
Vulnerability identifier: #VU158170
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-2026-117958
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 Networking: HTTP component when handling HTTP activity. A remote attacker can trigger crafted network activity 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-2026-117958
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