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Syscoin reports Bridge incident involving about 5B unauthori

Kucoin • June 8, 2026

Syscoin reports Bridge incident involving 5B unauthorized SYS outputs Syscoin said in a preliminary postmortem that its Bridge has been paused after a security incident involving 5B SYS. According to Syscoin, an attacker exploited a validation issue in the Bridge flow, causing the system to incorrectly accept or interpret a transaction proof and create 5B unauthorized SYS outputs through the UTXO Bridge path. The funds were moved and split after reaching the UTXO chain, with 4B SYS and 1B SYS linked to two major tainted addresses. Syscoin said it has identified the affected validation path, prepared a fix, and is coordinating with exchanges and ecosystem partners to blacklist, freeze or monitor SYS deposits connected to the tainted UTXO trail. Users are advised not to interact with the Bridge while it remains paused.

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Syscoin Bridge Exploit Results in 5 Billion Unauthorized Tokens Minted On June 8, 2026, Syscoin reported a security incident involving its cross-chain bridge, where an attacker exploited a validation flaw, minting approximately 5 billion unauthorized SYS tokens. The flaw occurred in the bridge relay path, which incorrectly accepted a fraudulent transaction proof, leading to the unauthorized output valued at nearly $10 million. The attacker moved the minted tokens to multiple wallets, with significant amounts split between two addresses. Syscoin has paused the bridge service and is working with exchanges to blacklist the affected tokens. The incident has caused a nearly 20% drop in SYS's market price, compounding existing losses for holders. This exploit highlights ongoing vulnerabilities in cross-chain systems, with similar incidents reported in the DeFi space. The Syscoin team has identified the issue and is preparing a fix pending security review. 19 sources 71

Syscoin reports Bridge incident involving about 5B unauthori

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