Cross-Chain Crisis? Why Wrapped BTC Might Be Bitcoin’s Weakest Link

Marvin Bertin has raised concerns about the security risks posed by bridges and wrapped assets. He warned that these solutions introduce vulnerabilities that compromise Bitcoin’s security model.

Bertin: Wrappers Are Worse

In the rapidly expanding world of decentralized finance, cross-chain solutions like bridges and wrapped assets have emerged as popular tools to enhance interoperability between blockchains. However, Marvin Bertin, co-founder and CEO at Maestro, recently issued a stark warning on X: “Bridges are risky! Wrappers are worse. If it’s not on Bitcoin, it’s not Bitcoin.” Bertin’s assertion zeroes in on fundamental security vulnerabilities that, from his perspective, fundamentally undermine the essence of Bitcoin’s security model.

The Maestro CEO’s primary concern revolves around centralized key control and the creation of single points of failure. He points directly to incidents like the Ronin Network hack, which saw over $540 million stolen, and the Wormhole bridge exploit, resulting in a loss of $320 million. These incidents, Bertin told Bitcoin.com News, were possible because these bridges, despite their complexity, relied on a limited set of signatories or custodians who controlled the underlying assets.

When these keys are compromised, the entire system can collapse, leading to massive financial losses. This directly contrasts with Bitcoin’s design, where control is distributed among a vast network of miners and nodes, making a single point of attack virtually impossible. Wrapped Bitcoin (wBTC), for instance, relies on custodians who hold the native BTC, reintroducing a layer of trust that Bitcoin was specifically designed to eliminate.

Beyond centralized control, Bertin highlights how these solutions “drastically expand attack surfaces through complex smart-contract logic.” Bridges and wrappers are often powered by intricate smart contracts that manage the locking, minting, and burning of tokens across different chains. The more complex the code, the higher the likelihood of unforeseen bugs, vulnerabilities, or logical flaws that can be exploited by malicious actors.

While Bitcoin’s scripting language is intentionally minimalist and highly battle-tested, cross-chain smart contracts often operate in less mature environments, increasing their susceptibility to sophisticated attacks. Each line of complex code represents a potential entry point for hackers, directly eroding the security posture that users might assume they inherit from the Bitcoin network.

According to Bertin, the introduction of a centralized key control and the complex smart-contract logic exposes wrapped BTC “to external consensus and contract risks,” thereby undermining Bitcoin’s minimal-assumption security model.

The Proposed Solution: UTXO DeFi

As a fundamental alternative to these risky cross-chain methods, Bertin proposes “UTXO DeFi” as the solution for “on-chain, trustless and secure” Bitcoin decentralized finance. He explains that UTXO DeFi directly leverages Bitcoin’s native unspent transaction output (UTXO) model, partially signed bitcoin transactions (PSBTs), and innovative metaprotocols like Runes and Ordinals. This approach enables projects to build secure, permissionless decentralized applications (dApps) directly on Bitcoin’s Layer 1 without resorting to bridges or wrappers.

Bertin shares examples such as Magic Eden, which utilizes PSBTs to facilitate secure trading of Runes and Ordinals, and Liquidium, which employs Discreet Log Contracts for non-custodial lending. These projects, he argues, demonstrate how on-chain solutions can preserve Bitcoin’s inherent security and trustlessness while enabling advanced financial functionalities.

Bertin nevertheless acknowledges that there are challenges to broader adoption of UTXO DeFi. These include a steep developer learning curve for UTXO scripting, which is a specialized form of programming for Bitcoin transactions. Additionally, there is limited tooling available for developers, and users may experience UX friction when navigating the complexities of crafting multi-party PSBT workflows, which are essential for many UTXO DeFi applications.

Addressing Industry Reliance on Bridges and Custodial Challenges

Meanwhile, when it was put to him that many projects already rely heavily on wrapped assets and cross-chain bridges for liquidity, Bertin insisted the industry does not fully comprehend the systemic risks involved. Instead, he identified an innovative solution and outlined his vision for DeFi.

“Innovations like intent-based solvers (e.g., Across, Uniswap X) now enable cross-chain swaps without bridging assets, eliminating much of the complexity that traditionally makes bridges vulnerable. My vision for a trust-minimized DeFi future is built on native, secure primitives,” Bertin stated.

Regarding challenges faced by custodians, banks or traditional finance (TradFi) institutions working with BTC or looking to add the crypto asset to their treasury, Bertin identified three key hurdles: regulatory uncertainty, operational and security complexity, and custody integration. According to Bertin, his company has a specialized platform that helps these institutions overcome the challenges whilst staying compliant.

“Maestro takes a partner-led approach to empower institutions to safely integrate Bitcoin into treasury and investment operations, while building internal expertise and confidence,” Bertin said.