A weakness in a system, application, or process that could be exploited to cause harm. Like an unlocked door in an otherwise secure building.
An unpatched web server running outdated software may have a known vulnerability that attackers can exploit to gain unauthorized access.
“Vulnerability” is a security concept, not a single cloud service. All major cloud providers offer vulnerability scanning and management tools to help find and remediate weaknesses in workloads, containers, and configurations.