CVE-2026-6755
Received Received - Intake
Mitigation Bypass in Firefox DOM postMessage Component

Publication date: 2026-04-21

Last updated on: 2026-04-22

Assigner: Mozilla Corporation

Description
Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
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Meta Information
Published
2026-04-21
Last Modified
2026-04-22
Generated
2026-06-16
AI Q&A
2026-04-21
EPSS Evaluated
2026-06-14
NVD
CVE-2026-6755
EUVD
EUVD-2026-24096
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
mozilla firefox to 150.0 (exc)
mozilla thunderbird to 150.0 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-352 The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
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Executive Summary

This vulnerability is a mitigation bypass in the DOM postMessage component of Mozilla Firefox. It means that a security measure intended to protect the postMessage functionality in the Document Object Model (DOM) could be circumvented by an attacker. The issue was fixed in Firefox version 150.

Impact Analysis

Exploitation of this vulnerability could allow an attacker to bypass security mitigations related to the postMessage component in Firefox. This might lead to unauthorized communication or data exchange between different origins in the browser, potentially exposing sensitive information or enabling further attacks.

Mitigation Strategies

The vulnerability is fixed in Firefox version 150. Immediate mitigation should include updating Firefox to version 150 or later.

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