
The latest firmware for GT-S5303B is S5303BVJANC1 with Android 4.0.4 (Ice Cream Sandwich), released on April 25, 2014 for 1 region (CSC). Every official firmware build for GT-S5303B, 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/S5303BVJANC1
All 3 builds in our database run Android 4.0.4 (Ice Cream Sandwich). The newest build, S5303BVJANC1, was released on April 25, 2014. No new build has appeared for 152 months, so regular updates for this model have most likely ended.

GT-S7508

GT-S6812

GT-S6500L

GT-S5690L

GT-S5670
The newest firmware for GT-S5303B runs Android 4.0.4 (Ice Cream Sandwich): build S5303BVJANC1, released on April 25, 2014.
The latest build for GT-S5303B, S5303BVJANC1, was released on April 25, 2014 (12 years ago).
GT-S5303B has had no new firmware for 152 months, so regular updates have most likely ended.
Yes, all firmware files for GT-S5303B are 100% official, original, and obtained directly from Samsung servers.
To flash GT-S5303B, 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 GT-S5303B.