Download iOS 11.2.1 (15C153) for iPhone SE

You will have to note that you can only restore signed IPSW firmware files using iTunes or 3utools.

❌ This IPSW firmware is not being Signed by Apple

Firmware Identifier iPhone8,4
iOS Version 11.2.1
Release Date 2017-12-13
Update Date 2017-12-10
Sha1sum
85124b66bb039b0740d7c8b61257abf1c1d07319
Sha256sum
abe2df1486b1e3f1480d6ba1029771a48665d4454e788a0d6abb8cd580e164be
md5sum
65cc098c56bd4ebc9aeb518f74d9b071
Size 2.43 GB
FileName
iPhone_4.0_64bit_11.2.1_15C153_Restore.ipsw
Status

Download IPSW (2.43GB) Check device info
Release Notes

It should be noted that these are the official release notes for the from Apple

iOS 11.2.1 fixes bugs including an issue that could disable remote access to shared users of the Home app.

For information on the security content of Apple software updates, please visit this website:

https://support.apple.com/kb/HT201222