Executive brief
Mozilla Firefox is a popular web browser used for accessing the internet. A security flaw in the browser's Service Workers component—a tool used to run background tasks for websites—could allow a malicious site to bypass built-in security protections. This could potentially lead to unauthorized access to data or the circumvention of privacy controls.
Technical details
A mitigation bypass vulnerability was identified in the DOM: Service Workers component of Mozilla Firefox. Service Workers are scripts that the browser runs in the background, separate from a web page, enabling features like push notifications and background sync. The vulnerability allows for the bypass of security mitigations designed to isolate or restrict Service Worker behavior. While specific exploitation details are restricted in the associated Bugzilla report (Bug 2044063), such bypasses typically involve circumventing the Same-Origin Policy or other sandbox constraints. The issue is resolved in Firefox 153.
Affected products
- Mozilla Firefox < 153
Timeline
- 2026-07-21: disclosed
- 2026-07-21: patched: Fixed in Firefox 153