STKR News0 of 3 free this monthAnother bridge falls victim to a flash loan exploit, draining $1.65 million. Here is what builders need to know about the math behind the Allbridge attack.
Originally on Decrypt →Adrian Boysel
Contributor
Jul 20, 2026
5 min read
Photo illustration / STKR News
We have seen this movie before. A cross-chain protocol wakes up to an empty wallet, a frantic engineering team pauses the bridge, and the community is left holding the bag while security researchers dissect the autopsy on Twitter. This time it is Allbridge, a protocol that facilitates transfers between EVM-compatible chains and non-EVM chains like Solana. The damage is roughly $1.65 million. While that is not a billion-dollar Ronin-level catastrophe, the mechanics of the theft reveal a persistent, structural weakness in how we build liquidity pools for bridges.
The exploit was not a sophisticated private key compromise or a social engineering trick. It was a math problem. Specifically, it was a manipulation of the internal price oracles used by Allbridge to determine exchange rates between stablecoins on different chains. According to security firms tracking the movement, the attacker utilized a flash loan to temporarily inflate their balance and distort the logic of the bridge's liquidity pools on Solana.
By injecting a massive amount of capital into the pool and then manipulating the swap function, the attacker convinced the protocol that the value of the assets they were withdrawing was much lower than reality, or conversely, that their deposit was worth significantly more. Once the pool's internal accounting was broken, they drained the liquidity and swapped the proceeds into Ethereum. This is the hallmark of a flash loan attack: if your protocol relies on a price point that can be moved within a single transaction block, you are effectively leaving your vault door unlocked for anyone with enough temporary capital to push it open.
For those of us building in this space, the Allbridge incident is a reminder that bridges are the weakest link in the current modular stack. If you are building a dApp that relies on bridged assets, you are inheriting the security risk of that bridge. If the bridge fails, your users' assets are essentially bricked, or at the very least, de-pegged from their intended value.
The issue here is the reliance on internal liquidity pools to facilitate cross-chain movement. Maintaining balanced pools across multiple ecosystems is a massive capital efficiency challenge. When those pools become shallow, the impact of a single large trade—or a malicious flash loan—is magnified. Builders need to move away from simplistic automated market maker (AMM) logic for cross-chain swaps unless they have robust, delay-based protections or external, manipulation-resistant oracles.
Allbridge did what most protocols do in this situation: they hit the kill switch. The protocol is currently paused as the team investigates the vulnerability and attempts to negotiate with the attacker. We often see these "white hat" invitations where the team offers a bounty in exchange for the return of the funds. It is a desperate move, but in the current regulatory and technical environment, it is often the only way to recover user capital.
The secondary effect of this pause is the erosion of trust. Every time a bridge goes down, the entire concept of a multi-chain future takes a hit. Users start to retreat back to centralized exchanges or stay within the confines of a single ecosystem like Ethereum or Solana. For a founder, the takeaway is clear: if you cannot guarantee the safety of the bridge, you cannot guarantee the viability of your product.
Why does this keep happening? I suspect it is a mix of technical debt and the pressure to ship features. In the race to support the newest L1 or L2, security audits often become a checkbox rather than a rigorous stress test. Flash loan attacks are not new. We have known about them for years. Yet, we still see protocols being deployed with logic that can be manipulated by high-frequency, high-capital transactions.
We need to stop treating security as a post-launch priority. In the bridge world, security is the only feature that actually matters. You can have the lowest fees and the fastest transaction times, but if the liquidity can be drained by a clever script, the protocol is a failure.
The Allbridge exploit is a symptom of a larger problem. We are trying to patch together disparate blockchains that were never meant to talk to each other. The middleware we use to bridge these gaps is brittle. As as an industry, we have a choice. We can continue to build these shallow liquidity pools and hope for the best, or we can move toward more secure architectures like atomic swaps or zero-knowledge proofs for state verification.
As long as we rely on pools of tokens sitting in a smart contract as a 'bridge,' we are essentially creating a honey pot for every sophisticated actor in the world.
I am not saying we should give up on bridges. They are necessary. But we have to be honest about the risks. If you are a founder, be skeptical of any protocol that claims to be "secure" without a multi-layered defense strategy. Don't just look at the audit certificate; look at the architecture. If a flash loan can move the price, it is not a bridge; it's a gamble.
The Allbridge team will likely find a way to patch the hole, and they might even get some of the money back. But the reputational damage is harder to fix. For developers, let this be the push to review your own oracle dependencies. If you are using a single source of truth for price data in an environment where capital can be borrowed for free (essentially), you are at risk. Build for the worst-case scenario, because in crypto, the worst-case scenario is just a matter of time.
Read the original at Decrypt →
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