Firefox 149 arrives with split view, tab notes, faster PDFs, and new security fixes
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Mozilla has released Firefox 149 to the stable Release channel, with the rollout starting on March 24, 2026. The update focuses on everyday browsing tools, built-in privacy improvements, and security hardening rather than one headline-grabbing change. Mozilla’s official release notes highlight split view, Tab Notes in Firefox Labs, faster PDF rendering through hardware acceleration, new translation languages, and a redesigned TrustPanel in the address bar.
Mozilla’s official notes and developer documentation for Firefox 149 list split view, Tab Notes, PDF acceleration, translation updates, TrustPanel changes, sharing improvements, autofill expansion, and developer-facing web platform additions, but the VPN claim did not appear in the official Firefox 149 materials I checked.
That makes Firefox 149 an important release, but for different reasons than the sample suggests. It improves multitasking, page trust visibility, translation coverage, and PDF performance while also shipping high-impact security fixes. Mozilla’s security advisory for Firefox 149 rates the release as high impact and lists multiple vulnerabilities, including memory safety bugs and graphics-related flaws.
What is new in Firefox 149
Mozilla says Firefox 149 adds Split View, which lets users place two pages side by side in a single browser window. The feature aims to make comparison, multitasking, and research easier without forcing users to jump between tabs. Mozilla also says Tab Notes is available in Firefox Labs, allowing users to attach notes to tabs to help keep track of tasks and references.
Firefox 149 also improves PDF performance. Mozilla says hardware acceleration now helps PDF files load faster, while the browser also expands on-device translation support with Bosnian, Norwegian Bokmål, Serbian, and Thai. In addition, Mozilla says users can add a Share button to the toolbar and that Address Autofill is now enabled in Australia, India, Italy, Poland, and Austria.
A more visible privacy and security change is the new TrustPanel. Mozilla says it combines privacy and security information into one panel accessible from the address bar, making it easier for users to review connection security and tracking protections in one place.
Security fixes are a major part of this release
Mozilla’s advisory for Firefox 149 lists a high-impact security release. The company says Firefox 149 fixes multiple vulnerabilities, including a race condition and use-after-free issue in WebRender, incorrect boundary conditions in Canvas2D, and memory safety bugs that Mozilla says showed evidence of memory corruption and could potentially be exploitable for arbitrary code execution.
That means Firefox 149 is not only a feature update. It is also an important browser security update that users should install promptly, especially if they are still on Firefox 148 or older builds.
Key Firefox 149 features at a glance
- Split View for side-by-side webpages in one window
- Tab Notes in Firefox Labs
- Faster PDFs through hardware acceleration
- TrustPanel for combined privacy and security info in the address bar
- On-device translation support for Bosnian, Norwegian Bokmål, Serbian, and Thai
- Share button support in the toolbar
- Address Autofill expansion to Australia, India, Italy, Poland, and Austria
- Developer-facing platform changes through the Reporting API and other web platform updates
Firefox 149 feature summary
| Area | What Mozilla added or changed |
|---|---|
| Productivity | Split View, Tab Notes |
| PDFs | Hardware acceleration for faster loading |
| Privacy and trust | New TrustPanel in the address bar |
| Translation | Added Bosnian, Norwegian Bokmål, Serbian, and Thai |
| Sharing | Optional Share button in toolbar |
| Autofill | Expanded address autofill support to five more countries |
| Security | Multiple high-impact vulnerability fixes |
Why the update matters
Firefox 149 looks like a broad quality-of-life release. Mozilla is improving how users compare pages, manage notes, review site trust, and work with PDFs, while also fixing vulnerabilities that could affect browser stability and security. That combination makes this a stronger release than a simple feature drop.
It also shows Mozilla continuing to push on-device features. Translation support stays local, Tab Notes lives inside the browser workflow, and TrustPanel makes privacy information easier to understand without sending users into deep settings menus.
FAQ
Firefox 149 is Mozilla’s stable browser release first offered to Release channel users on March 24, 2026.
Mozilla highlights Split View, Tab Notes in Firefox Labs, faster PDFs, TrustPanel, new translation languages, and sharing and autofill improvements.
Yes. Mozilla says Firefox 149 fixes multiple vulnerabilities and labels the advisory as high impact.
I could not verify that claim in Mozilla’s official Firefox 149 release notes or developer release materials. The official documentation I checked focused on browser features such as Split View, Tab Notes, TrustPanel, translation updates, PDF acceleration, and security fixes.
Anyone using Firefox on the Release channel should update, especially because the release includes both new features and high-impact security fixes.
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