Yahoo today confirmed that 450,000 unencrypted usernames and passwords were stolen Wednesday from one of its services, although it downplayed the threat. “We confirm that an older file from Yahoo! Contributor Network, previously Associated Content, containing approximately 450,000 Yahoo! and other company usernames and passwords was compromised yesterday, July 11,” Yahoo said in a statement forwarded by a company spokeswoman Thursday. “Of these, less than 5% of the Yahoo! accounts had valid passwords,” the company maintained. However, it did not say what percentage of the remaining accounts, which included over 100,000 Gmail addresses and more than 55,000 Hotmail addresses, included valid passwords. Read the full story at ComputerWorld.