
Samsung Galaxy S5 Neo
The latest firmware for Samsung Galaxy S5 Neo (SM-G903W) is G903WVLU1CQI1 with Android 7.0 (Nougat), released on October 2, 2017 for 15 regions (CSC). Every official firmware build for SM-G903W, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/G903WVLU1CQI1
SM-G903W started on Android 5 and has received 2 major Android upgrades; it now runs Android 7.0 (Nougat). The newest build, G903WVLU1CQI1, was released on October 2, 2017. No new build has appeared for 110 months, so regular updates for this model have most likely ended.
Box codes of SM-G903W for different colors and markets. Firmware is chosen by the model code SM-G903W and your region (CSC), not by the SKU.

SM-G903F

SM-G900AZ

SM-G9098

SM-G901F

SM-G800X
The newest firmware for SM-G903W runs Android 7.0 (Nougat): build G903WVLU1CQI1, released on October 2, 2017.
The latest build for SM-G903W, G903WVLU1CQI1, was released on October 2, 2017 (9 years ago).
SM-G903W has had no new firmware for 110 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G903W are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G903W, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-G903W.