A flaw in Core Lightning, software for Bitcoin's Lightning payment network, allows nodes to keep crashing on restart even after an upgrade if a previously stored malicious announcement is not manually removed from disk. The preventive patch was released in April with v26.04.1, but researcher Nishant Bansal's October 24 disclosure highlighted that the trigger remains on disk, affecting versions v25.02 through v26.04. Bitcoin Optech emphasized the issue on October 30.