# Cross-Chain Bridge Flaw Allows Attacker to Steal One Million Dollars ∞ Security

**Published:** 2025-11-10
**Categories:** Security

---

![The image displays a high-tech modular hardware component, featuring a central translucent blue unit flanked by two silver metallic modules. The blue core exhibits internal structures, suggesting complex data processing, while the silver modules have ribbed designs, possibly for heat dissipation or connectivity](https://incrypthos.com/wp-content/uploads/2025/09/next-gen-validator-node-hardware-for-sharded-blockchain-interoperability.jpeg)

![The image showcases a detailed view of futuristic, glowing blue circular modules integrated into a sleek, metallic apparatus. These highly detailed components feature intricate digital patterns and a vibrant blue luminescence, suggesting advanced technological processing](https://incrypthos.com/wp-content/uploads/2025/09/decentralized-network-architecture-visualizing-cryptographic-hashing-and-validator-nodes.jpeg)

## Briefing

The FEG Token Bridge was compromised via a critical flaw in its cross-chain message verification logic, allowing an attacker to execute unauthorized withdrawals across multiple chains. This exploit bypassed the intended security checks, leading to the theft of FEG tokens which were immediately swapped for native assets. The primary consequence is a direct $1 million USD loss, highlighting the systemic fragility of custom-built [interoperability](https://incrypthos.com/news/interoperability/) solutions.

![A large, irregularly shaped celestial body, half vibrant blue and half textured grey, is prominently featured, encircled by multiple translucent blue rings. Smaller, similar asteroid-like spheres, some partially blue, are scattered around, with one enclosed within a clear circular boundary, all against a gradient background transitioning from light to dark grey](https://incrypthos.com/wp-content/uploads/2025/09/decentralized-protocol-ecosystem-sharding-tokenomics-governance-model.jpeg)

## Context

The prevailing risk factor for cross-chain protocols remains the security of the message passing layer, as custom implementations often introduce novel attack surfaces not covered by standard smart contract audits. This particular bridge, while leveraging the Wormhole infrastructure for communication, introduced a proprietary [verification process](https://incrypthos.com/news/verification-process/) that became the single point of failure. The reliance on an unverified relayer contract for whitelisting was a known class of architectural risk in bridge designs.

![A sleek, silver-toned metallic mechanism is partially submerged in a vibrant, glowing blue liquid, surrounded by white foam. The central component features angular, robust designs, reflecting light and depth from the luminous blue substance, creating a sense of advanced engineering](https://incrypthos.com/wp-content/uploads/2025/09/Decentralized-Protocol-Component-Dynamic-Liquidity-Environment-Blockchain-Infrastructure.jpeg)

## Analysis

The attacker exploited an error in the FEG relayer contract’s logic, which failed to adequately verify the sourceAddress of a [cross-chain](https://incrypthos.com/news/cross-chain/) message. By sending a malicious message that designated the attack contract as an ‘admin’ and the sourceAddress as the attack contract, the attacker successfully added their contract to the bridge’s whitelist. This whitelist bypass rendered subsequent security checks ineffective, allowing the attacker to call the token withdrawal function and drain approximately $1 million USD in FEG tokens across Ethereum, Base, and BSC.

![Two large, fractured pieces of a crystalline object are prominently displayed, one clear and one deep blue, resting on a white, snow-like terrain. The background is a soft, light blue, providing a minimalist and stark contrast to the central elements](https://incrypthos.com/wp-content/uploads/2025/09/genesis-block-split-revealing-intrinsic-tokenomics.jpeg)

## Parameters

- **Total Loss (USD)** ∞ $1,000,000; Approximate total value of stolen [tokens](https://incrypthos.com/news/tokens/) across three chains.

- **Attack Vector** ∞ Cross-chain message [verification](https://incrypthos.com/news/verification/) flaw; The root cause was an error in the bridge’s custom message verification process.

- **Affected Chains** ∞ Ethereum, Base, and BSC; The [exploit](https://incrypthos.com/news/exploit/) was executed across all three chains managed by the bridge.

- **Stolen [Assets](https://incrypthos.com/news/assets/)** ∞ FEG tokens, ETH, and BNB; FEG tokens were withdrawn and immediately swapped for native chain assets.

![A prominent, glowing blue 'X' shape, appearing crystalline with internal digital patterns, is centrally positioned and slightly angled. It hovers above several stacked, metallic rectangular structures featuring illuminated blue lines and circuit-like designs](https://incrypthos.com/wp-content/uploads/2025/09/Blockchain-Interoperability-Protocol-Cryptographic-Primitives-Infrastructure-Visualization.jpeg)

## Outlook

Users must immediately cease all interaction with the compromised bridge and await an official post-mortem and remediation plan from the development team. This incident will likely trigger a renewed focus on standardized, formally verified cross-chain communication protocols, increasing the pressure on all custom bridge implementations to undergo rigorous, third-party security reviews of their message verification logic. The immediate second-order effect is a heightened contagion risk for any [protocol](https://incrypthos.com/news/protocol/) using similar whitelisting or custom relayer logic for cross-chain asset transfers.

![A striking abstract visualization showcases a translucent, light blue, interconnected structure with prominent dark blue reflective spheres. The composition features a large central sphere flanked by smaller ones, all seamlessly integrated by fluid, crystalline elements against a blurred blue and white background](https://incrypthos.com/wp-content/uploads/2025/09/decentralized-network-architecture-visualizing-cryptographic-primitives-and-digital-assets.jpeg)

## Verdict

**This exploit confirms that bespoke cross-chain message verification logic is a critical, high-value attack surface that mandates immediate, industry-wide re-auditing and a shift toward trustless, standardized interoperability primitives.**

Cross-chain bridge, message verification, smart contract logic, token withdrawal, unauthorized minting, multi-chain asset, bridge security, layer two interoperability, asset drain, protocol vulnerability, relayer contract, whitelist bypass, on-chain forensics, token price crash, liquidity pool, decentralized finance Signal Acquired from ∞ <a href="https://www.certik.com/resources/blog/5xV4QzGjK20-feg-bridge-exploit-technical-analysis?utm_source=incrypthos.com&utm_medium=referral&utm_campaign=noo-engine.com" target="_blank" rel="nofollow">certik.com</a> 

## Micro Crypto News Feeds

<a href="https://incrypthos.com/news/interoperability/" class="glossary-item-box">

## interoperability 

Definition ∞ Interoperability denotes the capability of different blockchain networks and decentralized applications to communicate, exchange data, and transfer value with each other seamlessly. </a><a href="https://incrypthos.com/news/verification-process/" class="glossary-item-box">

## verification process 

Definition ∞ A Verification Process is a systematic procedure for confirming the authenticity, accuracy, or validity of data, transactions, or identities within a system. </a><a href="https://incrypthos.com/news/cross-chain/" class="glossary-item-box">

## cross-chain 

Definition ∞ Cross-chain refers to the ability of different blockchain networks to communicate and interact with each other. </a><a href="https://incrypthos.com/news/tokens/" class="glossary-item-box">

## tokens 

Definition ∞ Tokens are digital units of value or utility that are issued on a blockchain and represent an asset, a right, or access to a service. </a><a href="https://incrypthos.com/news/verification/" class="glossary-item-box">

## verification 

Definition ∞ Verification is the process of confirming the truth, accuracy, or validity of information or claims. </a><a href="https://incrypthos.com/news/exploit/" class="glossary-item-box">

## exploit 

Definition ∞ An exploit refers to the malicious utilization of a security flaw or vulnerability within a protocol, smart contract, or application to gain unauthorized access, steal assets, or disrupt operations. </a><a href="https://incrypthos.com/news/assets/" class="glossary-item-box">

## assets 

Definition ∞ A digital asset represents a unit of value recorded on a blockchain or similar distributed ledger technology. </a><a href="https://incrypthos.com/news/protocol/" class="glossary-item-box">

## protocol 

Definition ∞ A protocol is a set of rules governing data exchange or communication between systems. </a>

**Tags:** [Asset](https://incrypthos.com/news/asset/), [On-Chain Forensics](https://incrypthos.com/news/on-chain-forensics/), [Token Price](https://incrypthos.com/news/token-price/), [Relayer Contract](https://incrypthos.com/news/relayer-contract/), [Contract Logic](https://incrypthos.com/news/contract-logic/), [Risk](https://incrypthos.com/news/risk/)	

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**Tags:** [Asset](https://incrypthos.com/news/asset/), [Asset Bridge](https://incrypthos.com/news/asset-bridge/), [Asset Drain](https://incrypthos.com/news/asset-drain/), [Assets](https://incrypthos.com/news/assets/), [Bridge](https://incrypthos.com/news/bridge/), [Bridge Security](https://incrypthos.com/news/bridge-security/), [Contract](https://incrypthos.com/news/contract/), [Contract Logic](https://incrypthos.com/news/contract-logic/), [Cross-Chain](https://incrypthos.com/news/cross-chain/), [Cross-Chain Bridge](https://incrypthos.com/news/cross-chain-bridge/), [Decentralized Finance](https://incrypthos.com/news/decentralized-finance/), [Exploit](https://incrypthos.com/news/exploit/), [Interoperability](https://incrypthos.com/news/interoperability/), [Layer Two](https://incrypthos.com/news/layer-two/), [Layer Two Interoperability](https://incrypthos.com/news/layer-two-interoperability/), [Liquidity Pool](https://incrypthos.com/news/liquidity-pool/), [Message Verification](https://incrypthos.com/news/message-verification/), [Multi-Chain Asset](https://incrypthos.com/news/multi-chain-asset/), [On-Chain Forensics](https://incrypthos.com/news/on-chain-forensics/), [Protocol](https://incrypthos.com/news/protocol/), [Protocol Vulnerability](https://incrypthos.com/news/protocol-vulnerability/), [Relayer Contract](https://incrypthos.com/news/relayer-contract/), [Risk](https://incrypthos.com/news/risk/), [Security](https://incrypthos.com/news/security/), [Smart Contract](https://incrypthos.com/news/smart-contract/), [Smart Contract Logic](https://incrypthos.com/news/smart-contract-logic/), [Token](https://incrypthos.com/news/token/), [Token Price](https://incrypthos.com/news/token-price/), [Token Price Crash](https://incrypthos.com/news/token-price-crash/), [Token Withdrawal](https://incrypthos.com/news/token-withdrawal/), [Tokens](https://incrypthos.com/news/tokens/), [Unauthorized Minting](https://incrypthos.com/news/unauthorized-minting/), [Verification](https://incrypthos.com/news/verification/), [Verification Process](https://incrypthos.com/news/verification-process/), [Whitelist Bypass](https://incrypthos.com/news/whitelist-bypass/)

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**Original URL:** https://incrypthos.com/security/cross-chain-bridge-flaw-allows-attacker-to-steal-one-million-dollars/
