S921NKSSIEZJ1 – Galaxy S24 firmware
Build S921NKSSIEZJ1 is a security update for the Galaxy S24 (SM-S921N)
on Android 17 (One UI 9). It first appeared on Samsung's servers on Oct 21, 2026 (method) and has reached
4 regions so far. It raises the bootloader bit from 17 to 18: once installed, the device no longer accepts firmware with bit 17 or lower, so a downgrade to S921NKSUHEZIF is blocked. Samsung still serves this file.
- Model
- SM-S921N
- Android
- Android 17
- Type
- Security
- Bootloader bit
- 18
- First released
- Oct 21, 2026
- Regions
- 4
Rollout timeline by region
The date each region code (CSC) first received S921NKSSIEZJ1, counted from the first release.
| CSC | Region | Released | Rollout | Version (PDA/CSC/MODEM) |
|---|---|---|---|---|
KOO | South Korea | Oct 21, 2026 | day 0 | S921NKSSIEZJ1/S921NOKRIEZJ1/S921NKSSIEZJ1 |
KTC | South Korea (KT) | Oct 21, 2026 | day 0 | S921NKSSIEZJ1/S921NOKRIEZJ1/S921NKSSIEZJ1 |
LUC | South Korea (LG U+) | Oct 21, 2026 | day 0 | S921NKSSIEZJ1/S921NOKRIEZJ1/S921NKSSIEZJ1 |
SKC | South Korea (SKT) | Oct 21, 2026 | day 0 | S921NKSSIEZJ1/S921NOKRIEZJ1/S921NKSSIEZJ1 |
Download and release notes
samloader download -m SM-S921N -r KOO -v S921NKSSIEZJ1/S921NOKRIEZJ1/S921NKSSIEZJ1Samsung's release notes and security patch level for this update: SM-S921N / KOO on doc.samsungmobile.com. What each part of the build number means: decode S921NKSSIEZJ1.