CVE-2026-6755 Mitigation bypass in the DOM: postMessage component

Description

Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

Affected products and versions

Product	Affected versions	Fixed in
Firefox 150	earliest → < 150	150
Thunderbird 150	earliest → < 150	150

Other CVEs of Firefox

The 2221 CVEs of Firefox →

CVE-2026-120572 Incorrect boundary conditions in the Layout: Block and Inline component 8.8 High CVE-2026-118027 Frame poisoning in the Layout component 9.1 Critical CVE-2026-118025 Other issue in the SVG component 8.8 High CVE-2026-118026 Invalid pointer in the JavaScript: GC component 8.8 High