BTCPay Server restricts remote Lightning connections following exploit

BTCPay Server has temporarily restricted public remote connections to Lightning Network nodes running Lightning Network Daemon (LND) software after attackers exploited a critical vulnerability to obtain credentials and move funds.

BTCPay said the restriction prevents external wallets such as Zeus from connecting through a BTCPay Server domain or Tor onion address on Docker deployments. BTCPay said Lightning payments can continue and that it plans to restore the remote-access option when it considers it safe.

Version 2.4.2 installs LND version 0.21.1 and automatically regenerates the macaroon credentials on standard BTCPay installations. The project advised operators to check for unauthorized payments, unexpected channel closures, unfamiliar peers and discrepancies in their onchain or Lightning balances.

The BTCPay breach is the latest security incident involving widely used Bitcoin products, following a Coldcard hardware-wallet flaw linked to more than $100 million in confirmed losses. The separate incidents affected software surrounding Bitcoin rather than the network’s underlying protocol.

Update automatically rotates Lightning credentials

BTCPay said the vulnerability allowed an unauthenticated remote attacker to obtain “macaroon” credential files used to control LND, an implementation of the Lightning Network. The project said the exposed credentials could allow attackers to take control of an LND node and move its funds.

According to the project’s security advisory, version 2.4.2 installs LND version 0.21.1 and automatically regenerates macaroon credentials on standard BTCPay installations. It advised operators to check for unauthorized payments, unexpected channel closures, unfamiliar peers and discrepancies between their records and onchain or Lightning balances.

BTCPay also said operators exposing LND through their own reverse proxy, Tor service, forwarded port, or another route outside BTCPay must rotate their credentials separately. The project said installing the update does not close access routes managed independently by the operator.

At least two operators publicly reported losses. Foundation CEO Zach Herbert said the hardware-wallet company’s Lightning node was drained overnight. He later clarified that its hot wallet was unaffected, while its Lightning channels were closed and the funds swept.

Bitcoin publication Citadel21 also reported that its Lightning node had been swept. Neither operator disclosed the amount lost.