CVE-2026-84139

Modified Modified - Updated After Analysis

Clickjacking in Firefox DOM Events Component

Publication date: 2026-09-01

Last updated on: 2026-09-03

Assigner: Mozilla Corporation

Description

Clickjacking issue in the DOM: Events 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

2026-09-05

AI Q&A

2026-09-01

EPSS Evaluated

2026-09-03

NVD

CVE-2026-84139

EUVD

EUVD-2026-69087

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-1021	The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain, which can lead to user confusion about which interface the user is interacting with.

Attack-Flow Graph

Executive Summary

This is a clickjacking vulnerability in the DOM Events component of Firefox and Firefox ESR. Clickjacking occurs when an attacker tricks a user into clicking on a malicious link or button that is invisible or disguised, potentially allowing unauthorized actions to be performed on a trusted website.

Detection Guidance

Detection involves checking Firefox version. Run: firefox --version. If version is below 155 or Firefox ESR below 153.2, the system is vulnerable.

Impact Analysis

An attacker could exploit this to trick you into clicking on harmful elements without your knowledge, leading to actions like changing account settings, making unauthorized transactions, or exposing sensitive data.

Compliance Impact

The vulnerability does not provide specific details about compliance impacts. Clickjacking can potentially expose user data, which may affect GDPR compliance by violating data protection principles. HIPAA compliance could be impacted if patient data is exposed through such attacks.

Mitigation Strategies

Update Firefox to version 155 or later and Firefox ESR to 153.2 or later. Disable JavaScript if possible as a temporary workaround.

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