Mitigation Bypass in the postMessage Component of Firefox by Mozilla
CVE-2026-6755

6.5MEDIUM

Key Information:

Vendor

Mozilla
Status
Firefox
Vendor
CVE Published:
21 April 2026

What is CVE-2026-6755?

A mitigation bypass vulnerability has been identified in the postMessage component of Firefox. This vulnerability could potentially allow the execution of unauthorized scripts or content through the compromised messaging system. Users are encouraged to update to Firefox version 150 or later, where this issue has been addressed to enhance security and integrity of web communications.

Affected Version(s)

Firefox 150

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1880429
https://www.mozilla.org/security/advisories/mfsa2026-30/

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

paranoidmoth
.