Zen Browser 1.22.2b Lands on Firefox 156, Riding a 67-CVE Security Patch
Zen Browser's latest stable update ships the full Firefox 156 security haul, and it's here four days after the previous release. The new build, tagged 1.22.2b, went live on GitHub today. It's a straightforward point release in the grand scheme, but the security half of the equation is worth paying attention to.
The big news is what's under the hood. Zen 1.22.2b upgrades its engine to Firefox 156.0, which bundles Mozilla's advisory MFSA2026-90. That advisory covers 67 fixed CVEs: 27 rated high severity, 20 moderate, and 20 low. Since Zen is built directly on Firefox's codebase, users inherit all of these fixes in a single update. You don't need to chase anything separately.
It's a rather unusual number to see in a release note, but there's a reason. Mozilla now publishes one advisory per individual bug instead of rolling several vulnerabilities into a single CVE. That long list of 67 mostly reflects a policy change, not a sudden explosion of fresh flaws.
What actually changed in this build
On the feature side, the changes are modest. macOS users get an auto-start option you can toggle from the Startup section of Settings, so Zen launches when your Mac boots. Zen also added five new command-bar actions: expand the current view, open a new space, reopen a closed tab, duplicate a tab, and reset a pinned tab.
The fixes are where most of the daily-pain relief lives. There's a fix for subtitles disappearing from Picture-in-Picture windows when you turn them on after PiP is already open. Split View no longer bricks its find bar after you reverse the panes. DNS-over-HTTPS sites that don't support HTTPS will load again, and Windows users won't find the taskbar held hostage when it's set to auto-hide.
Cross-device sync was also patched. Tabs created too quickly were sometimes getting lost during sync. There's a separate fix for a browser freeze when routing tabs across spaces. And live folders stop lying about being active when they're empty.
The performance notes are the most concrete claim here. Zen says its built-in PDF viewer now starts up to 45% faster. It also trimmed memory and CPU use for large JPEGs scaled down to fit a page, and Windows ARM64 users get hardware H.264 decoding for WebRTC calls instead of a software fallback.
Not cheap to achieve in terms of effort, but these are exactly the tiny annoyances that make a browser feel worth keeping open.
The version numbering thing worth knowing
If the "b" in 1.22.2b looks odd, here's the insider bit. That suffix traces back to Zen's beta-channel numbering scheme. But this tag is published with prerelease: false and draft: false, meaning it's a normal stable build, not a pre-release. So installing it is safe if you care about staying current on that CVE list.
Why Zen matters in the first place
For those not following the project, Zen is a free, open-source browser that skins and extends Firefox under the Mozilla Public License 2.0. You get workspaces to split tabs by project, compact mode to hide the tab bar, Glance to jump between favorite tabs without digging through history, Split View for two tabs at once, and a mods system for customization. It's a genuinely useful set of ideas for people who let browser tabs multiply.
The security angle is worth calling out specifically. Open-source doesn't automatically mean secure, but Zen's approach of riding Firefox's engine directly means it gets the heavy lifting done by a team with far more resources. When Mozilla ships 67 fixes, Zen rides along within days rather than waiting for a separate backport job. That's a real advantage for users who want the polish of Zen without the upkeep of chasing every upstream patch by hand.
It's a rather expensive-feeling update in one sense, though not price. It's an update that delivers mostly under-the-hood correctness and security rather than headline features. But for a browser you keep open for hours at a time, the faster PDF loading and the fixed sync bugs probably matter more than a shiny new command anyway.
Zen Browser 1.22.2b is available now on GitHub. Head here to download the release.
