Download iOS 15.3.1 (19D52) for iPhone 13 Pro Max

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 iPhone14,3
iOS Version 15.3.1
Release Date 2022-02-10
Update Date 2022-02-07
Sha1sum
eff9521dd5f5193babb37886749a950b56153e7d
Sha256sum
7b2ee10e6a2331d8805162c479dc04e7f920b570670a1416ea88788c3bcf2eae
md5sum
f849922f76fdd16ca43b98211f3f5a67
Size 6.20 GB
FileName
iPhone14,3_15.3.1_19D52_Restore.ipsw
Status

Download IPSW (6.20GB) Check device info
Release Notes

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

iOS 15.3.1 provides important security updates for your iPhone and fixes an issue that may cause Braille displays to stop responding.

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

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