A new One UI 9.5 test build for the Galaxy S26 Ultra has surfaced on Samsung’s servers, according to Kailash. The build ends in ZZK3, and it adds to the earlier internal testing that we covered when Samsung started testing One UI 9.5 on the Galaxy S26. Samsung hasn’t announced a beta program or a release date, so a test build only shows that the work is moving along.
| Detail | Info |
| Phone | Galaxy S26 Ultra, international model (S948B) |
| PDA build | S948BXXU6ZZK3 |
| CSC build | S948BOXM6ZZK3 |
| Phone (CP) build | S948BXXU6CZK3 |
| Bootloader | Moved from U5 to U6 |
| Seen on | Samsung’s servers, including Korea and the US |
| Beta program | Not announced, possibly late November or early December |
| Changelog | Not available |
The three build strings are parts of one software package for a single model, not three different phones. S948B is the international Galaxy S26 Ultra, so the build doesn’t show that the S26 and S26+ received the same firmware, even though internal One UI 9.5 testing has covered the wider series. The jump from a U5 to a U6 bootloader suggests Samsung moved to a newer revision, which tends to happen as a major update gets closer to release, but that is an interpretation and not something Samsung has said. The K in ZZK3 points to November.
Current reports say the beta could open later in November or in early December, though that is an estimate and Samsung hasn’t confirmed any date. The S26 series is expected to be first, with the Galaxy S25 series, Z Fold 8 and Z Flip 8 mentioned by one report as later candidates, but there is no official eligibility list. One UI 9.5 is still expected to run on Android 17, and Samsung hasn’t published a changelog, so none of the new features are known. One early rumor so far is App Lock coming in One UI 9.5, though that is also unconfirmed.
The stable version is expected to debut on the Galaxy S27 series in January or February 2027, with the S26 getting it a few weeks after the new phones launch. That timing follows Samsung’s usual pattern and isn’t a confirmed schedule. Meanwhile, the S26 series is still rolling out stable One UI 9, and the test build isn’t available to download.
M Adnan Akram is the founder and lead writer at Phoonomo, covering mobile technology with a primary focus on Samsung and the broader smartphone industry, alongside emerging developments in AI. He follows product launches, spec leaks, and industry trends closely to keep readers informed with timely updates.
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