
Samsung GALAXY S Ⅲ
The latest firmware for Samsung GALAXY S Ⅲ (SGH-T999L) is T999LUVUBOH1 with Android 4.3 (Jelly), released on August 12, 2015 for 1 region (CSC). Every official firmware build for SGH-T999L, 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/T999LUVUBOH1
All 2 builds in our database run Android 4.3 (Jelly). The newest build, T999LUVUBOH1, was released on August 12, 2015. No new build has appeared for 136 months, so regular updates for this model have most likely ended.

SGH-I927

SGH-S730M

SGH-T999N

SGH-T989D

SGH-T859
The newest firmware for SGH-T999L runs Android 4.3 (Jelly): build T999LUVUBOH1, released on August 12, 2015.
The latest build for SGH-T999L, T999LUVUBOH1, was released on August 12, 2015 (11 years ago).
SGH-T999L has had no new firmware for 136 months, so regular updates have most likely ended.
Yes, all firmware files for SGH-T999L are 100% official, original, and obtained directly from Samsung servers.
To flash SGH-T999L, 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 SGH-T999L.