CVE-2026-84133

Analyzed Analyzed - Analysis Complete

DOM Push Subscription Isolation Flaw in Firefox

Publication date: 2026-09-01

Last updated on: 2026-09-03

Assigner: Mozilla Corporation

Description

Site isolation issue in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-01

Last Modified

2026-09-03

Generated

2026-09-21

AI Q&A

2026-09-01

EPSS Evaluated

2026-09-20

NVD

CVE-2026-84133

EUVD

EUVD-2026-69081

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 153.2.0 (exc)
mozilla	firefox	From 154.0.0 (inc) to 155.0.0 (exc)
mozilla	thunderbird	to 153.2.0 (exc)
mozilla	thunderbird	From 154.0 (inc) to 155.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-346	The product does not properly verify that the source of data or communication is valid.

Attack-Flow Graph

Executive Summary

This is a site isolation issue in the DOM Push Subscriptions component of Firefox. It was patched in Firefox 155 and Firefox ESR 153.2. The flaw could allow unauthorized access or manipulation of push subscription data between different sites.

Detection Guidance

This vulnerability is specific to Firefox 155 and Firefox ESR 153.2. To detect it, check your Firefox version using commands like 'firefox --version' or 'about:support' in Firefox. If your version is below 155 (standard) or 153.2 (ESR), the system is vulnerable.

Impact Analysis

An attacker might exploit this to intercept or alter push notifications, leading to data leaks or misinformation. Users could see unauthorized messages or have sensitive data exposed if they rely on push notifications for critical updates.

Compliance Impact

This could violate data protection requirements under GDPR or HIPAA if push subscription data includes personal or health information. Organizations must ensure patches are applied to avoid non-compliance penalties.

Mitigation Strategies

Update Firefox to version 155 or later and Firefox ESR to version 153.2 or later to address the DOM Push Subscriptions site isolation issue.

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