Firefox 136 Brings Vertical Tabs, Enhanced Security, and New Sidebar Features
Mozilla’s Firefox 136 update introduces a number of exciting changes, including vertical tabs, improved security features, and a sleek sidebar redesign that enhances the overall user experience. For those with numerous tabs open, the vertical tabs stacked in the sidebar will help keep everything organized and visible, making it easier to manage multiple tasks at once.
On the security front, Mozilla has patched at least 15 vulnerabilities, including five with a high-risk rating in the 2025-14 Security Advisory. CVE-2025-1930, a critical vulnerability, could enable attackers to break out of the browser’s sandbox on Windows devices. Other high-risk vulnerabilities could result in arbitrary code execution and crashes, presenting significant risks to user safety. These updates apply to Firefox ESR and Tor Browser as well, keeping your browsing secure across various platforms.
In addition to vertical tabs, Firefox 136 includes a new sidebar that can hold bookmarks, history, and tabs from other synced devices. A key feature in the sidebar is direct access to an AI chatbot, providing users with an easy way to interact with intelligent assistants. The sidebar is customizable—moving from left to right—and can even house browser extensions, provided developers add support.
If you’re tired of clicking through tabs, enabling vertical tabs in the sidebar will stack them in a clean, organized list, making it easier to navigate through open pages. This can be set up via the sidebar customization options.
Additionally, Firefox now uses HTTPS-First by default, automatically attempting to open pages over HTTPS for better security. If that fails, the browser will fall back to HTTP. This adds an extra layer of protection when browsing.
Mozilla Responds to Terms of Use Changes
In late February, Mozilla updated its Terms of Use to reflect changes in how it handles collected data. Although some users raised concerns and speculated about the changes, these were primarily made to align with new legal requirements across U.S. states and don’t signify any drastic shifts in Mozilla’s data collection practices.
Firefox ESR and Tor Browser Updates
As part of its ongoing support, Mozilla has also updated Firefox ESR versions 128.8.0 and 115.21.0, addressing multiple vulnerabilities in each release. Additionally, Tor Browser 14.0.7, based on Firefox ESR 128.8.0, is now available. For users running Windows 7 or 8.1 or macOS 10.13/10.14, the update to Tor Browser 13.5.13 is also available.
Mozilla has confirmed that Firefox ESR 115 will be supported until September 2025, with plans for possible extension. As for Tor Browser 13.5.x, the future of its support is uncertain and will be discussed at a later date.