BOSTON (AP) — Computer security experts around the world are racing to patch one of the worst software vulnerabilities discovered in years. The critical flaw is in an open-source utility widely used by government and industry. Experts say it is already being exploited and the fallout won’t be known for several days. Untold millions of servers have the Java-language code installed. It is used by Apache servers to log user activity. Cybersecurity experts say users of the online game Minecraft have already exploited it to breach other users by pasting a short message into in a chat box.