Microsoft warned users that it discontinued support for Windows XP starting on April 8, 2014 users running Windows XP afterwards would be at the risk of attacks. As security patches of newer Windows versions can reveal similar (or same) vulnerabilities present in both newer and older Windows versions, this can allow attacks on devices with unsupported Windows versions (cf. "zero-day attacks"). However Microsoft stopped fixing such (and other) vulnerabilities in unsupported Windows versions, regardless how widely known such vulnerabilities became, leaving these vulnerabilities unfixed and devices running these Windows versions vulnerable to attacks. Microsoft made a singular exception during the rapid spread of the WannaCry ransomware and released patches in May 2017 for the by then-unsupported Windows XP, Windows 8, and Windows Server 2003 (in addition to then supported Windows versions).