Parity Multisig Wallet Freeze

What happened

Parity's multi-signature wallets did not each carry their own logic. To save deployment cost, every wallet was a thin contract that delegated its behaviour to one shared library contract on the network. That library had been deployed without being initialised, so its ownership was still unclaimed. In November 2017 a user claimed it and then invoked its self-destruct function, which removed the library's code from the chain. Every wallet that depended on it was left pointing at nothing: the balances still exist in the ledger, but the code that could authorise a transfer no longer does. Public estimates put the amount stranded at roughly 513,000 ETH. Nobody took the funds, and no exploit moved them; they simply stopped being reachable. Proposals to recover them by protocol change were debated and not adopted. Months earlier, a separate flaw in the same wallet software had allowed an actual theft of around 150,000 ETH by public estimates.

What to take from it

Not every loss involves a thief. Shared code is a shared dependency, and a contract that delegates to a library inherits that library's failure modes without saying so on the tin. It also shows the limit of immutability from the user's side: the same property that stops anyone rewriting your balance stops anyone repairing it, and an unrecoverable mistake can be as expensive as an attack.

Dates and figures are widely reported public estimates from coverage at the time, not KripZen's own audited data.