Protection mechanism failure in Mozilla products - CVE-2026-100821
Published: September 29, 2026
Vulnerability identifier: #VU152829
CSH Severity: Low
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-2026-100821
CWE-ID: CWE-693
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass site isolation.
The vulnerability exists due to improper site isolation in the Panning and Zooming component when it is used. A remote attacker can trigger the site-isolation issue to bypass site isolation.
Affected software
Firefox for Android
Mozilla Firefox
Firefox ESR
Mozilla Firefox
Firefox ESR
How to mitigate CVE-2026-100821
Install security update from vendor's website.
Firefox for Android - update to 157.0
Mozilla Firefox - update to 157.0
Firefox ESR - addressed in versions 115.42.0, 140.17.0, 153.4.0
Mozilla Firefox - update to 157.0
Firefox ESR - addressed in versions 115.42.0, 140.17.0, 153.4.0