Taiko halted block production on its Ethereum layer-2 network on June 22 after an attacker used an RSA-3072 private key the team had committed to a public GitHub repository to forge bridge withdrawal proofs and drain approximately $1.7 million.
The team had accidentally pushed enclave-key.pem, the signing credential for its SGX trusted-execution enclave, to the public taikoxyz/raiko repository, according to CryptoTimes. No cryptographic flaw was exploited; the attacker used a plaintext secret left in a public repo.
The attacker used the leaked key to register forged SGX provers and generate fake L2 state attestations. Because Taiko's L1 contracts accept any enclave whose public key matches the stored MrSigner value, the spoofed proofs passed on-chain verification. The attacker then called processMessage() to mark withdrawal requests as retriable and retryMessage() to release funds from both the L1 bridge and ERC20Vault contracts, per CryptoTimes. The attacker routed about 2 million TAIKO tokens to the MEXC exchange.
Taiko said the exploit was contained by about 2 a.m. ET, paused the bridge and ERC20Vault, and stopped block producers from building new blocks while it investigates, according to CoinDesk. Remaining bridge funds are secure, the team said; it is working with exchanges to track and freeze attacker assets and is preparing a full post-mortem. Security firm BlockSec identified the exposed Raiko SGX enclave key on GitHub as the root cause, CoinDesk reported.
TAIKO fell more than 20% from midnight UTC on the day of disclosure, per CoinDesk. Bridge and block production remain paused as of the team's last update, with no timeline given for restoration.
The attack belongs to a recurring class of bridge exploits built on forged proof submissions. Most 2026 bridge losses trace to credential failures, not protocol cryptography flaws.
