Alexa, the voice assistant used by millions of smart gadgets including Amazon’s popular Echo lineup, uses what it calls Skills to carry out commands. You ask if rain is coming, for example, and Alexa uses the “Weather” Skill to answer.

Researchers from security testing firm Checkmarx found a flaw with Alexa that allowed a Skill to continue listening long after a person activated the software, said Amit Ashbel, director of product marketing for Checkmarx.

“As far as we could tell, there was no limit,” Ashbel said. “As long as you don’t tell it to stop, it wouldn’t.”