Critical security problem in UpdraftCentral: an attacker holding the service’s keys planted a backdoor on our websites

On the night of 19 October 2026 an attacker abused UpdraftCentral, the remote management service built into UpdraftPlus, a backup plugin with more than 4 million installations, and planted a backdoor on two of our three websites. Our sites were fully up to date and the fault was not on our side: the attacker signed the commands with valid keys that the UpdraftCentral Cloud service generates and keeps. We publish an analysis of the backdoor, indicators of compromise and a way to check your own sites.