While later versions of the Wii System Menu patched this vulnerability, IOS36 version 3351 retained it. Because IOS36 was required by many popular games (like Mario Kart Wii and Super Smash Bros. Brawl ), it was present on millions of consoles.
Complete Softmod Guide - DOP-Mii
because newer official updates from Nintendo (like those found in system menu 4.2 or 4.3) patched the Trucha bug. cIOS Installation ios36-64-v3351.wad
: Version 3351 is specifically used in homebrew to re-enable the "Trucha Bug." This bug allows the system to run unsigned (unauthorized) code. While later versions of the Wii System Menu
: Developers use it to "patch" the system, allowing for the installation of custom channels and backup loaders. ios36-64-v3351.wad