When I study a chain, one question matters above all: can it get hacked? Let me say this up front: Ethereum is an excellent chain. It created the programmable general-purpose chain, and its flexible account model powered the entire DeFi explosion. This post uses a few real security incidents as comparison points to make one argument: for building smart contracts and crossing chains, Cardano’s approach is, in my view, more advanced.

The DAO reentrancy: a structural flaw, and a structural answer

In 2016, The DAO lost about $60 million in Ethereum, splitting the community into a hard fork. The bug was reentrancy: in the account model, “send money to the counterparty” and “update the balance” are two steps with a time gap, and the attacker keeps calling the withdraw function inside that window.

flowchart TB
    A[Contract sends money to attacker] --> B[Attacker contract calls back<br/>and withdraws again]
    B --> C[Balance not yet deducted<br/>so a third withdrawal]
    C --> D[The account model<br/>has this middle state]

This bug exists because of the account model’s shared, mutable state: balances are global and changeable, and execution can be interrupted halfway. The eUTXO answer is structural — which old outputs a transaction spends and which new ones it creates are fixed before submission, and script validation runs once to completion. There’s no “mid-withdrawal” state at all. For the same functionality, eUTXO trades away “state can’t change casually” and removes an entire class of bugs. That’s where I think it’s more advanced.

The Parity freeze: the convenience of changeable, and the peace of immutable

In 2017, a developer accidentally triggered selfdestruct on Parity’s wallet library contract, permanently freezing over $150 million worth of ETH (partially unlocked later through an upgrade).

The incident exposed the hidden risk of the shared-library + upgradeable contract pattern: every multisig wallet depended on one shared library that also carried upgrade powers. Kill the library, and everyone suffers.

Cardano’s choice is immutable once on-chain: a script is locked by a hash as part of the transaction, with no upgrade backdoor, so there’s no “library rewritten into poison code” or “backdoor planted in a library.” For application layers, being changeable is convenient; for the base rules that hold money, immutability is the more advanced answer — the cost being that bugs can’t be quietly patched, only fixed by deploying a new version and asking users to migrate.

Bridge thefts: keeping the core small is the more advanced architecture

The biggest losses in recent years all happened on cross-chain bridges, not on the chains themselves:

• Wormhole (2022): ~$326M, a flaw in signature verification.
• Ronin (2022): ~$625M, validator private keys stolen through social engineering.
• BNB Token Hub (2022): ~$586M, forged IAVL Merkle proofs minted 2 million BNB out of thin air.

These incidents share one trait: bridges are third-party infrastructure, with verification logic implemented by the bridge itself, outside the core chain. To see why, look at a bridge’s trust structure:

flowchart TB
    subgraph 链A[Chain A]
        A1[Assets locked in a contract]
    end
    subgraph 桥[Third-party bridge]
        B1[A set of validators / light client<br/>watching the other chain]
        B2[Verification logic<br/>implemented by the bridge]
    end
    subgraph 链B[Chain B]
        C1[Mints wrapped assets 1:1]
    end
    A1 --> B1 --> B2 --> C1

The BNB bridge is the most instructive case: its verification used IAVL Merkle proofs, but the proof check was incomplete, so an attacker could inject forged leaves and still pass, minting 2 million BNB. The verification logic wasn’t implemented correctly — exactly what provable security is meant to guard against.

Cardano made provable security its foundation: the core consensus’s safety is backed by mathematical proofs, not by “we got audited” rhetoric. Keep the core small, rigorous, and provable; leave the complexity to third parties. That’s the architecture I consider more advanced.

The honest part: even the most advanced approach can’t stop a third party’s own bug

Let’s be honest here. In July 2026, the Wanchain Cardano–BNB bridge on Cardano’s ecosystem lost about 515 million NIGHT tokens. Security firm BlockSec traced the root cause: the bridge’s TreasuryCheck validator built its signed message by concatenating 14 fields with no delimiters, so different field combinations could produce identical byte strings — letting an attacker reuse one valid signature to forge withdrawals.

In other words: core chain security is not ecosystem security. No matter how advanced the approach, a third party can still ship its own bug — the Midnight Foundation also confirmed the protocol itself was unaffected. What Cardano can do is keep its core small, rigorous, and provable, not bail out every third party.

The real boundary

After this comparison, a few classes of incidents aren’t preventable by any approach:

• Ronin-style private key theft: a validator hands over keys or gets phished — that’s key management, not protocol. No chain should carry that blame.
• Business-logic bugs: a miswritten smart contract can still be drained on Cardano. What changes is that classic techniques like reentrancy, front-running, and shared-state arithmetic overflow no longer apply.

Cardano’s design doesn’t promise “never hacked.” It promises “a specific class of classic vulnerabilities is structurally impossible.” Its ceiling is staked on provable consensus and immutable contracts; the rest of the boundary is human.

Excellent, and more advanced

After these comparisons, my conclusion is: Ethereum traded freedom and speed for an ecosystem explosion, and that success is well earned. Cardano traded some expressiveness for a design where reentrancy, self-destructed libraries, and forged proofs are structurally impossible. Two different trade-offs, and for a settlement layer meant to carry long-term value, I believe Cardano’s approach is more advanced. It can’t stop every attack, but it guarantees the classic plays can’t land. The remaining boundary is human and operational.

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