There aren’t many details available yet, but you can find some information here: https://treblle.com/blog/jlr-breach-breakdown-analysis

The main issue appears to be that the attack crippled JLR’s internal systems and production databases, preventing them from manufacturing new cars because they cannot properly track parts or generate serial numbers.

I’ve also read reports claiming that around 40k vehicles have already been built but are now essentially “ghost cars” since they aren’t registered in the system.

Imagine what would happen if JLR had to issue a safety recall without knowing which components are installed in which vehicles.