Mozilla Releases Firefox 153 ESR With Profile Management, Split View, and On-Device AI Features for Enterprise

Mozilla has released Firefox 153 Extended Support Release (ESR), first made available to ESR channel users on July 21, 2026, according to Mozilla's release notes.

This update includes all changes since Firefox 140 ESR, such as a new profile management system, Split View, enhanced fingerprinting protection, AES-256 password encryption, and on-device AI features. Firefox 140 ESR will continue to receive security updates during the transition period until users are automatically upgraded to Firefox 153 ESR.

Mozilla recommends that enterprise administrators test Firefox 153 ESR with their current configurations, extensions, authentication systems, and deployment tools before the automatic upgrade.

Profile Management, Split View, On-Device AI Features, and Enterprise Controls

Firefox 153 ESR introduces a profile management system that separates browsing into distinct profiles, each with its own name, avatar, and color theme. Tabs, bookmarks, passwords, and browsing history remain separate for each profile. The release also adds built-in profile backup and restore to support device migration or data recovery.

Split View allows users to view two webpages side by side in a single window, open links directly in Split View, rearrange pages, and search open tabs. The address bar now includes unit and time zone conversion, quick actions such as muting all browser audio, and displays search results as the user types. Firefox also supports copying links to highlighted text, and the Settings interface has been reorganized.

Firefox 153 ESR introduces several AI-powered features, including on-device tab organization, AI-assisted link previews, integrated AI search, and centralized controls for managing AI features. Mozilla states that these features process data locally where possible to protect user privacy.

In managed environments, enterprise administrators can centrally manage Firefox's generative AI features through enterprise policy. This allows administrators to disable or restrict AI features across deployments instead of leaving the choice to individual users.

Security, Privacy, and Platform-Specific Changes

Firefox 153 ESR expands security protections. Fingerprinting Protection is now broader in both Standard and Strict Enhanced Tracking Protection modes, making it more difficult for sites to uniquely identify users.

Enhanced Tracking Protection also adds stronger safeguards against bounce tracking and restricts websites from accessing local network resources without user permission.

Phishing and malware protection now use Safe Browsing V5, and the Firefox Password Manager uses AES-256 encryption to protect stored logins. Private Browsing now allows users to instantly end a session and temporarily relax tracker blocking for individual sites when needed for compatibility.

Several updates are specific to each operating system.

On Windows, Firefox now supports installing websites as standalone web apps pinned to the taskbar. Web apps are available through Microsoft Store installations, and geolocation requests now integrate more effectively with Windows location permissions.

On macOS, Firefox now uses a dedicated GPU process by default, allowing graphics failures to recover without restarting the browser. WebGPU is also enabled by default on Apple Silicon Macs.

On Linux, Firefox supports native fractional scaling on Wayland, no longer requires a restart after package manager updates, uses less memory, supports the XDG Base Directory Specification, and now provides RPM packages for Red Hat, Fedora, openSUSE, and other RPM-based distributions.

Steps for Administrators Preparing for the Upgrade, Web Platform Updates, and Availability

Enterprise administrators managing Firefox ESR deployments should test the new release before the automatic upgrade from Firefox 140 ESR is applied:

1. Deploy Firefox 153 ESR in a test environment and validate existing enterprise policies, as AI features and other defaults have changed.
2. Confirm that extensions, authentication systems, and native messaging integrations function as expected. Mozilla notes that a native messaging performance regression was fixed in this release.
3. Review generative AI policy controls and determine whether to disable or restrict AI features across the deployment.
4. Update references to enterprise policy documentation, now located at firefox-admin-docs.mozilla.org.
5. Apply the AppUpdatePin policy to hold back upgrades on specific machines during testing if necessary.

Testing during the transition window allows administrators to identify and report issues before users are automatically upgraded from Firefox 140 ESR to Firefox 153 ESR.

Firefox 153 ESR adds support for the View Transitions API, expands WebGPU support to Windows and Apple Silicon Macs, and introduces several modern web platform APIs, including the Navigation API, URLPattern, Trusted Types, the Sanitizer API, and Prioritized Task Scheduling.

Mozilla has not announced the exact date when Firefox 140 ESR users will be automatically upgraded to Firefox 153 ESR. Firefox 140 ESR will continue to receive security updates until the transition is complete.

Administrators who need to delay the upgrade can pin the update, but Firefox 140 ESR will eventually reach end of support, after which security updates will stop.

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Posted Saturday 25 July 2026 at 7:32 am AEST (my time).

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