- In an exploit, Syscoin’s bridge experienced approximately 5 billion unauthorized SYS.
- The project is monitoring related funds and developing a plan to halt the affected funds through the exchanges.
- The developers have sorted out the problem and are working on implementing a fix and an assessment of recovery.
Syscoin is currently investigating a major incident of bridge security that resulted in an estimated 5 billion unauthorized SYS tokens on the network’s UTXO side.
The project has suspended bridge operation and is in a concerted effort to contain the effects of the exploit with exchanges and ecosystem partners.
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Validation Flaw Triggered Unauthorized SYS Creation
According to a preliminary postmortem published by Syscoin, the incident originated from a bridge relay process that incorrectly accepted or interpreted a transaction proof.
Preliminary Postmortem: Syscoin Bridge Incident
We want to provide the community with a preliminary upd ate regarding the recent Syscoin bridge incident involving approximately 5B SYS.
The Syscoin bridge is currently paused while the team investigates, finalizes the fix, and…
— Syscoin (@syscoin) June 7, 2026
This causes the bridge to accept an invalid transaction as valid and to generate an invalid UTXO output valued at approximately 5 billion SYS via the UTXO bridge transaction route.
The reverse said that they didn’t panic about a direct hack of wallets or user accounts being responsible for this exploit. In fact, the problem was how the bridge approved transaction data in between chains.
The unauthorized output was initially transferred to a single address before being redistributed into multiple wallets.
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Syscoin Moves to Contain the Damage
Upon discovery of the incident, Syscoin immediately halted the bridge functions to stop further abuse until the investigation was done.
It has reached out to exchanges, infrastructure providers and ecosystem partners to identify and block any transactions related to affected funds, the project said.
Tainted Balances Spread Across Multiple Wallets
The one with the largest spread of balances known, based on the latest findings, is in two addresses with about 4 billion SYS and 1 billion SYS respectively.
It is actively tracking people who might be holding those tokens, as well as potentially any descendant transactions on the original exploit path, Syscoin said, and is monitoring that.
The team also suggests that exchanges blacklist or closely track deposits tied to the outputs that were compromised to limit the potential spread of the tokens.
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Team Confirms Fix as Investigation Continues
Syscoin indicated that it already discovered that the cause of the incident is on the validation path and has a ready remediation fix.
Focus is now on reviewing and deploying the patch, deciding on how to deal with the unearthing of the token supply by the exploit.
The incident brings the number of cases involving bridge hacks to the crypto sector to an ever-increasing list. Cross-chain infrastructure is one of the most appealing features for attackers due to its bridging of liquidity between various blockchain ecosystems and the fact that it typically uses intricate verification processes.
Users have been warned not to access the Syscoin bridge yet. More information will be available when the remediation process and recovery plan are finalized, the team said.
