MAP Protocol’s Butter Bridge V3.1 was exploited allowing an attacker to mint roughly 1,000,000,000,000,000 MAPO tokens and sell part of the newly created supply into liquidity. The attack triggered a sharp collapse in MAPO’s price and forced the team to pause cross-chain operations while it works on a patch, external audit and redeployment plan.
The exploit did more than extract value from a liquidity pool. It severely damaged MAPO’s supply economics, because the minted amount exceeded the pre-exploit circulating supply by millions of times and left a massive token overhang in the attacker’s wallet.
Hi @mapprotocol, you may want to take a look: huge amount 1,000,000,000,000,000 of $MAP0 were minted:https://t.co/gTl5TGRC9a pic.twitter.com/er6yh1Mh8b
— PeckShield Inc. (@peckshield) May 20, 2026
Packed Data Bug Breaks Bridge Verification
The attacker exploited an abi.encodePacked hash collision in the bridge’s OmniServiceProxy retryMessageIn routine. The bridge relied on a packed hash to validate retry messages, but the Solidity encoding method can concatenate dynamic byte fields without length prefixes or 32-byte padding.
That design flaw meant different input combinations could produce the same keccak256 digest. By rearranging byte-field boundaries while preserving the same packed output, the attacker passed the guard check with a forged retry message.
The sequence began with a cross-chain message that cached a NotContract retry commitment at a precomputed empty address. The attacker then deployed a contract at that exact address, satisfying later checks before calling retryMessageIn with manipulated field boundaries.
The resulting packed data produced the same 601-byte string and identical hash, allowing the forged message to pass as legitimate. That verification failure opened the path to unauthorized MAPO minting at a scale far beyond the token’s existing supply.
Tokenomics Collapse After Liquidity Dump
On-chain traces show the attacker minted about 1 quadrillion MAPO, roughly 4.807 million times the legitimate circulating supply of about 208 million MAPO. The attacker then sold 1 billion MAPO into the Uniswap V4 ETH/MAPO pool, extracting about 52.21 ETH, or roughly $180,000, before liquidity collapsed.
Post-mint figures showed total supply anomalies near 999,999,553,084,442 MAPO. The attacker was left holding roughly 999.999 trillion MAPO, creating an overwhelming supply overhang that immediately undermined market confidence.
MAPO had traded near $0.003 before the attack, but reports placed the post-exploit decline between 30% and 48%, with the token falling to roughly $0.001558. The price damage reflected panic selling and the effective breakdown of token scarcity, not only the ETH extracted from the pool.
MAP Protocol and Butter Network paused the bridge between MAPO ERC-20 on Ethereum and the native mainnet to prevent further exploitation. The teams also warned users to avoid trading MAPO on DEXes during the incident while patching, audit and redeployment workstreams proceed.
Security firm Blockaid described the root cause as a “Pure Solidity abi.encodePacked footgun.” That assessment underscores how a well-known development pitfall can produce outsized consequences when embedded inside cross-chain message verification.
For MAP Protocol, remediation is likely to be complex. A token migration or engineered redenomination would require governance coordination, exchange alignment and significant technical validation, especially given the scale of unauthorized supply now visible on-chain.
The broader lesson is clear for bridge developers and auditors. Cross-chain systems need stricter supervision of packing logic and message-format verification, with conservative use of abi.encodePacked wherever dynamic fields are concatenated.
The next operational steps are a formal post-mortem, an external audit of the patched bridge code and coordination with exchanges and liquidity providers. How MAP Protocol handles the supply overhang will determine whether confidence can be rebuilt after an exploit that damaged tokenomics more than it drained liquidity.
