The XKJ patch isn’t a firmware version you’ll see in Nintendo’s patch notes. It’s an internal code name (likely derived from a developer's initials or an internal bug ID) for a low-level mitigation that targets a specific TrustZone vulnerability in the Tegra X1 chip’s boot ROM — not the famous Fusée Gelée, but a later, more obscure flaw in the key derivation process.
If that’s the case, here’s an interesting, concise take on the topic: In the underground world of Switch modding, few things spread faster than a new untethered exploit — and few things kill it more quietly than a patch named "XKJ."
