A seven-year-old flaw in the Zilliqa Ledger app lets attackers reconstruct a user's private key from roughly five signatures in seconds. The vulnerability affects every version of the app released between 2019 and 2026, but only for native, non-EVM transactions signed through the app. Zilliqa detected on-chain activity consistent with active exploitation on July 19 and confirmed the root cause two days later.
How the randomness error works
The bug lives in the signing routine for Schnorr signatures on native transactions. The routine generated 40 bytes of randomness but copied the wrong 32-byte range into the nonce, fixing the highest 64 bits at zero. That makes the nonce predictable. An attacker who collects about five affected signatures signed by the same private key can combine them and reconstruct that key in seconds using commodity hardware. The weakened signatures stay on-chain permanently—updating the app can't erase that information.
Discovery and immediate response
Zilliqa noticed suspicious on-chain activity on July 19 and traced it to the flaw. KuCoin reported the incident and helped confirm the vulnerability. In response, Zilliqa suspended native, non-EVM transactions to stop further exploitation. A corrected version of the Ledger app is being prepared. The company stressed that EVM and official SDK signing paths are not affected, nor is the general security of Ledger hardware compromised.
What affected users need to do
Any account that has broadcast roughly five or more native transactions signed through the Zilliqa Ledger app should be considered compromised. The only safe move is to retire the affected private keys completely. A normal rescue transfer—moving funds to a new key—could be front-run by an attacker who has already reconstructed the old key, so users must act carefully. Zilliqa has not disclosed how many accounts are at risk.
The fix and what remains unresolved
The upcoming corrected app will prevent the bug from creating new weak signatures, but the signatures already on-chain remain vulnerable. Users who never used the app for native Zilliqa transactions are safe. The broader question—how many attackers have already exploited the bug—hasn't been answered publicly. Users with potentially affected accounts should check their transaction history and move funds to a fresh key as soon as the network allows.
