Firefox 154 release notes for enterprise admins

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Firefox 154

Released 18 August 2026.

These changes apply to Firefox 154 and Firefox ESR 153.1.0 unless explicitly stated. Firefox ESR 153 is the current ESR.

Firefox moves from a four-week to a two-week release cycle beginning with Firefox 155. Bug fixes, updates and features reach users more quickly once they are ready to ship.

New in Firefox 154

• CNSA2KeyAgreementEnabled: Enable the CNSA 2.0 ML-KEM-1024 key agreement for TLS. Does not apply to the ESR. (bug 2052296)
• DefaultBrowserSettingEnabled: Prevent users from changing the default browser. (bug 2051921)

Changes

• SanitizeOnShutdown: Added an Exceptions option to configure sites whose data should not be cleared on shutdown. Firefox 154 only. (bug 2049937)

Fixes

• SearchEngines: PreventInstalls did not prevent users from manually adding search engines in Settings or from the context menu. (bug 2052965)
• The -width and -height command-line options did not correctly set the Firefox window size. Firefox 154 only. (bug 1635927)
• Extended Protection (channel and service binding) for Windows SSPI authentication worked when using SPNEGO but not when using Kerberos directly. (bug 1179722)