Syscoin pauses bridge after exploit mints 5 billion unauthorized SYS tokens

Syscoin hit the pause button its bridge as it became the latest casualty of an exploit rampage that has ripped through DeFi in the last three months after exploiters minted five billion SYS tokens without any authorization or zero backing. 

Going by CoinMarketcap price data around the time the exploit was reported, the minted tokens would have set the project back by around $9 million. 

According to Syscoin’s first postmortem of the incident, the alleged attackers exploited a validation flaw in the project’s cross-chain bridge to create roughly 5 billion unauthorized SYS tokens. As part of its initial response, the team said it has freezed the bridge and is coordinating with exchanges to prevent the funds from being cashed out via the venues.

How was Syscoin exploited?

According to documentation, Syscoin operates a dual-chain architecture. 

• One is a Bitcoin-based UTXO chain 
• The other is an Ethereum-compatible smart contract chain called NEVM. 

The bridge that connects both Syscoin layers allows tokens to move after it verifies transaction proofs.

Syscoin’s preliminary postmortem implicated this system, writing that it “wrongly accepted a transaction proof,” treating a fraudulent submission as legitimate and minting approximately 5 billion SYS on the UTXO side.

Syscoin traced the initial output to a single address before the attacker divided it into two wallets at a 4 billion to 1 billion SYS split.

SYS token’s 2026 gets worse 

Syscoin’s SYS token has not had a vintage 2026, and it has continued that downward trend since the June 7 exploit, enduring a double-digit percentage point drop in the 24 hours since the disclosure. 

At the time of writing, about 12% value has been withdrawn per the token’s market cap metric, down to about $1.47 million as of June 8, which is good enough for the 1,720th spot among tokens tracked by CoinMarketCap. 

Notably, the unauthorized five billion tokens the exploiters minted dwarf Syscoin’s circulating supply of 891 million SYS by roughly five.

On the protocol side, Syscoin has not done much better this year either. Defillama shows the chain’s total value locked in DeFi protocols at effectively zero, with only 14 active addresses and 73 transactions recorded over the prior 24 hours.

When will Syscoin’s bridge return online?

As of this report, the Syscoin bridge remains offline. Users were also warned to avoid interacting with the bridge until further notice.

However, the team said it is now focused on implementation, code review, and determining how to neutralize the unauthorized supply after it identified the flawed validation path and prepared a fix. 

“Our priority now is to complete implementation and review of the fix, while also determining the correct process to rectify the unauthorized SYS output and neutralize its impact on the network,” the team wrote.

According to the messaging, Syscoin is currently prioritizing containing the fallout from the exploit so that its team and broader network don’t absorb those losses. Part of the plan includes talking with exchanges and ecosystem partners to blacklist tainted addresses or freeze deposits. 

Bridge exploits continue to plague crypto in 2026

The Syscoin incident lands in what has been a punishing year for cross-chain infrastructure. PeckShield reported that as of June 1, 14 major bridge and cross-chain exploits in 2026 had drained a cumulative $340.7 million, according to Cryptopolitan’s earlier reporting on June hack trends.

In May alone, CertiK counted 60 confirmed security incidents across the crypto industry totaling $68.3 million in gross losses, per Cryptopolitan’s monthly roundup. Bridge exploits accounted for $28.62 million of that figure, the largest dollar amount by incident type. Code vulnerabilities drove 66% of the month’s losses at $45.13 million.

The Syscoin exploit fits the pattern. A validation bug in bridge infrastructure, unauthorized token creation, and rapid movement of funds across addresses. Whether exchanges can freeze the tainted SYS before any reaches open markets will determine how much damage ultimately reaches holders.

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