Samsung has started testing One UI 9.5, the software update due after this year’s One UI 9.0, and it is doing so on two different Galaxy phones at once.
Tipster Fahad Ali Javed found the first sign of it on 2 August: a firmware build, numbered AZH3, tied to the Galaxy S27 Ultra, a flagship Samsung has not announced yet. A week later, a second build appeared. This one, numbered CZH1, is tied to the Galaxy S26 series, the flagship already on shelves in Kenya since March. Samsung leakers Ice Universe and Tarun Vats both posted about the S26 build.
For readers who don’t follow Samsung’s software calendar closely, that pairing needs unpacking.
Why two devices, not one
One UI is Samsung’s own interface, layered on top of Android. Every Galaxy phone runs it, and Samsung updates it on a yearly cycle, then follows with a smaller “.5” update roughly six months later. This year that cycle is One UI 9.0, which Samsung announced on 22 July and began rolling out to the Galaxy Z Fold 8, Z Fold 8 Ultra and Z Flip 8 on 7 August. One UI 9.5 is the step after that.
I've heard Samsung has started One UI 9.5 development for the Galaxy S26 Series, with a build version ending in CZH1.
Last year, One UI 8.5 development for the S25 Series started around mid-September.
This year, Samsung seems to be moving much faster. 👀
The Galaxy S26 already runs One UI 8.5 out of the box, and Samsung opened its One UI 9.0 beta to S26 owners back in May. A One UI 9.5 test build appearing on S26 hardware now points to Samsung preparing an eventual update path for people who already own the phone.
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The Galaxy S27 Ultra is a different case. Samsung has not announced it, and its model number, SM-S958U, exists only in leaks and test servers so far. Samsung typically builds its “.5” software using next year’s unreleased flagship as the primary test device, then ships that software pre-installed when the phone launches. On that pattern, One UI 9.5 is expected to arrive on the Galaxy S27 series when it launches, likely in early 2027.
This dual-track testing isn’t new for Samsung. The same thing happened with One UI 8.5. GSMArena reported a build for the Galaxy S25 Ultra in July 2025, while Samsung was separately developing One UI 8.5 for the then-unannounced Galaxy S26. The S26 went on to launch with One UI 8.5 already installed, in February 2026, which is the same rollout we tracked as it later expanded to budget Galaxy phones like the A06 5G.
What this means for Galaxy owners in Kenya
Nothing changes today for Galaxy S26 owners. Test builds like CZH1 and AZH3 run on Samsung’s internal servers and cannot be installed, even by people who go looking for them. Tarun Vats has suggested a public beta for One UI 9.5 could open to Galaxy S26 owners towards the end of the year, though Samsung has not confirmed that timeline, and we’d treat it as an estimate rather than a date to plan around.
Once any beta or stable release for One UI 9.5 does open up, open-market Galaxy devices in Kenya typically get it first. Phones bought on a carrier plan tend to follow a few weeks later, since the carrier tests the software on its own network before releasing it to customers.
Samsung has not commented on either build and has not confirmed a feature list for One UI 9.5. We’re tracking every confirmed One UI 9.0 build and rollout milestone separately, and will do the same for One UI 9.5 once more of it is verified rather than leaked.
What to watch
The build numbers themselves aren’t the story. What matters is that Samsung is now running One UI 9.5 on two Galaxy generations at once, seven months before the newer one is expected to exist as a retail phone. Samsung gave itself that same head start with One UI 8.5, and it’s the clearest signal yet of Samsung’s timeline for the Galaxy S27.
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