HDwallet question

[abhilodha]

Lets say i have 12 word seed and it can generate many addresses for bitcoin lets say i leaked my single private key of one of those addresses.

Is it possible for anyone to steal funds from other addresses? Or know the 12 word seed?

[ranochigo]

No. However, this is possible if you're using an unhardened derivation path and the master public key is also leaked. It would result in the master private key being derived from a combination of master public key as well as a child private key.

You won't know the 12 word seed even if you get the master private key but I imagine you won't really have any reason for that either.