Syscoin remains under pressure after attackers exploited a validation flaw in its cross-chain bridge and minted 5 billion unauthorized SYS tokens.
The project paused the bridge, warned users to stay away, and began working with exchanges to block tainted funds.
The incident has raised fresh concerns about Syscoin’s future as bridge attacks hit cross-chain protocols in 2026.
Exploit Exposes Bridge Validation Weakness
Syscoin said its early review found that the bridge wrongly accepted a transaction proof and treated a fraudulent submission as valid.
That error allowed the attacker to create roughly 5 billion SYS tokens on the Bitcoin-based UTXO side of the network.
Syscoin uses a dual-chain structure that includes a Bitcoin-style UTXO chain and an Ethereum-compatible smart contract chain known as NEVM.
Its bridge connects both layers and verifies transaction proofs before tokens move between them. The exploit targeted that verification process, according to preliminary findings.
The unauthorized output was traced to one address before being split into two wallets. One wallet received 4 billion SYS, while the other received 1 billion SYS.
The Syscoin team has disclosed the wallets holding the five billion tokens minted in the exploit. Source: Syscoin via X/Twitter
Based on CoinMarketCap price data near the time of the disclosure, the minted supply was worth about $9 million.
SYS Token Faces More Market Pressure
SYS has already had a difficult 2026, and the exploit added another blow to market confidence. The token dropped by double digits after the June 7 disclosure as traders reacted to the scale of the unauthorized mint.
Syscoin has endured a poor 2025 in terms of price even before the exploit. Source: CoinMarketCap
At the time of reporting, Syscoin’s market value had fallen by about 12% to nearly $1.47 million, placing it around 1,720th among assets tracked by CoinMarketCap.
The unauthorized 5 billion SYS also exceeded the circulating supply of about 891 million SYS by more than five times.
Network activity remains weak as well. DefiLlama data showed Syscoin’s DeFi total value locked at effectively zero, while the chain recorded only 14 active addresses and 73 transactions over the previous 24 hours.
Team Works On Fix And Fund Controls
The Syscoin bridge remains offline while developers complete the fix and review the affected validation path. The team said users should not interact with the bridge until further notice.
TVL has dropped to zero since its 2022 peak above $10 million. Source: Defillama
Syscoin said its current focus is implementation, code review, and a process to neutralize the unauthorized output. It is also coordinating with exchanges and ecosystem partners to freeze deposits, blacklist tainted addresses, and stop the attacker from cashing out.
The case adds to a costly year for bridge security. PeckShield reported 14 major bridge and cross-chain exploits had drained $340.7 million by June 1, while CertiK counted $68.3 million in crypto losses during May. Bridge incidents accounted for $28.62 million of that figure, with code flaws driving most losses.
