
Samsung Galaxy Core Plus
The latest firmware for Samsung Galaxy Core Plus (SM-G350M) is G350MNXUAOD1 with Android 4.3 (Jelly), released on April 15, 2015 for 1 region (CSC). Every official firmware build for SM-G350M, 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/G350MNXUAOD1
All 5 builds in our database run Android 4.3 (Jelly). The newest build, G350MNXUAOD1, was released on April 15, 2015. No new build has appeared for 140 months, so regular updates for this model have most likely ended.
Specifications of SM-G350, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G3509

SM-G3589W

SM-G357M

SM-G3568V

SM-G355M
The newest firmware for SM-G350M runs Android 4.3 (Jelly): build G350MNXUAOD1, released on April 15, 2015.
The latest build for SM-G350M, G350MNXUAOD1, was released on April 15, 2015 (11 years ago).
SM-G350M has had no new firmware for 140 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G350M are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G350M, 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-G350M.