Malleability is already fixed. Segwit does not fix it further.
Technical point: This is very much not the case: Malleability is blocked in the relay network for a narrow class of transactions but anything clever is exposed, multisig is exposed to other-signer malleation, and all transactions are exposed to malleation by miners. Segwit fixes it in a deep and profound way for all purely segwit transactions.
What relay network are we referring to here?
Does segwit still not provide a solution to malleation by miners for
on-chain transactions? Just curious because it sound's Malleability is only "blocked" on the "relay" network. How is consensus enforced in this relay network? Can i run a "relay network" node? Is the "relay network" open sourced?