The SMBv1 protocol in Microsoft Windows contains a remote code execution vulnerability that allows attackers to execute arbitrary code on the target system by sending specially crafted messages to the SMBv1 server. This vulnerability is particularly dangerous as it can be exploited without any user interaction and has been used in major ransomware attacks such as WannaCry.
The vulnerability exists in the way SMBv1 handles certain types of requests. A successful attack could allow an attacker to install programs; view, change, or delete data; or create new accounts with full user rights on the affected system.