CVE-2026-6755
published 2026-04-21CVE-2026-6755: Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
PriorityP433medium6.5CVSS 3.1
AVNACLPRLUINSUCNINAH
EPSS
0.19%
8.8th percentile
Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
Affected
4 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 150 | Firefox 150 |
| mozilla | firefox | < 150.0 | 150.0 |
| mozilla | thunderbird | < Thunderbird 150 | Thunderbird 150 |
| mozilla | thunderbird | < 150.0 | 150.0 |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vendor_redhat6.5MEDIUM
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Red Hat
firefox: Mitigation bypass in the DOM: postMessage component
vendor_redhat·2026-04-21·CVSS 6.5
CVE-2026-6755 [MEDIUM] CWE-807 firefox: Mitigation bypass in the DOM: postMessage component
firefox: Mitigation bypass in the DOM: postMessage component
A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
Mitigation bypass in the DOM: postMessage component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: firefox (Red Hat Enterprise Linux 10) - Not affected
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Not affected
Package: firefox (Red Hat Enterprise Linux 6) - Not affected
Package: firefox (Red Hat Enterprise Linux 7) - Not affected
Package: firefox (Red Hat Enterprise Linux 8) - Not affected
Package: firefox (Red Hat Enterprise Linux 9) - Not affected
Mozilla
Mozilla Foundation Security Advisory 2026-30: CVE-2026-6755
vendor_mozilla·CVSS 6.5
CVE-2026-6755 [MEDIUM] Mozilla Foundation Security Advisory 2026-30: CVE-2026-6755
Mozilla Foundation Security Advisory 2026-30
CVE: CVE-2026-6755
Product: Firefox
Impact: high
Fixed in: Firefox 150
Mozilla
Mozilla Foundation Security Advisory 2026-33: CVE-2026-6755
vendor_mozilla·CVSS 6.5
CVE-2026-6755 [MEDIUM] Mozilla Foundation Security Advisory 2026-33: CVE-2026-6755
Mozilla Foundation Security Advisory 2026-33
CVE: CVE-2026-6755
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 150
GHSA
GHSA-g672-5549-fj5x: Mitigation bypass in the DOM: postMessage component
ghsa_unreviewed·2026-04-21
CVE-2026-6755 [MEDIUM] CWE-352 GHSA-g672-5549-fj5x: Mitigation bypass in the DOM: postMessage component
Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150.
No detection rules found.
No public exploits indexed.
2026-04-21
Published