The Sandbox announced that it has contained a vulnerability on SAND’s cross-chain bridge on Base and BNB Smart Chain, after an attacker minted unbacked SAND on both networks.

According to security firm Blockaid, the first to detect the incident, the attacker hijacked LayerZero delegate permissions via the approveAndCall function, then proceeded to mint across more than 400 transactions with a total notional value of nearly $49 billion. On-chain analytics firm PeckShield recorded approximately 14.9 billion SAND minted to two attacker addresses.

For its part, The Sandbox provided a far more modest figure: direct damage under 0.01% of the 3 billion SAND total supply. The project asserted that SAND locked on Ethereum, the backing asset for all bridged tokens, remains intact and that no user wallets were compromised. The two figures are billions of dollars apart, and so far no independent party has confirmed the final picture.

To prevent the counterfeit SAND from being moved or swapped for real assets, the project completely shut down two-way bridging with Base and BSC. This leaves SAND on both networks currently isolated, unable to be transferred or redeemed. The Sandbox also warned holders not to buy, sell, or trade SAND on the two networks because liquidity there has been compromised. The project is taking pre-incident snapshots and preparing a compensation plan for eligible liquidity providers, along with a promise to publish a full post-mortem.

In the South Korean market, Bithumb suspended SAND deposits and withdrawals at 11:11 a.m. KST, with Upbit following just one minute later, citing suspected security issues under the Virtual Asset User Protection Act. Notably, Upbit also halted the Ethereum version of SAND, which The Sandbox itself later confirmed was never at risk.

The incident follows a familiar pattern in 2026. According to DefiLlama, this month alone has seen 17 separate exploits, mostly small in scale, with bridges continuing to be a recurring vulnerability. For The Sandbox, the episode once again raises questions about permission design on cross-chain infrastructure: a hijacked delegate function was enough to generate tens of billions of dollars in phantom tokens across a few hundred transactions.