
Samsung Galaxy A5(2017)
The latest firmware for Samsung Galaxy A5(2017) (SM-A520K) is A520KKKU8CTK1 with Android 8.0.0 (Oreo), released on November 24, 2020 for 1 region (CSC). Every official firmware build for SM-A520K, 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/A520KKKU8CTK1
SM-A520K started on Android 6 and has received 2 major Android upgrades; it now runs Android 8.0.0 (Oreo). The newest build, A520KKKU8CTK1, was released on November 24, 2020. No new build has appeared for 72 months, so regular updates for this model have most likely ended.
Box codes of SM-A520K for different colors and markets. Firmware is chosen by the model code SM-A520K and your region (CSC), not by the SKU.

SM-A520X

SM-A526N

SM-A528N

SM-A525M

SM-A530X
The newest firmware for SM-A520K runs Android 8.0.0 (Oreo): build A520KKKU8CTK1, released on November 24, 2020.
The latest build for SM-A520K, A520KKKU8CTK1, was released on November 24, 2020 (5 years ago).
SM-A520K has had no new firmware for 72 months, so regular updates have most likely ended.
Yes, all firmware files for SM-A520K are 100% official, original, and obtained directly from Samsung servers.
To flash SM-A520K, 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-A520K.