New OS X exploit breaks Keychain’s security, exposes passwords
A new exploit discovered by researchers from Indiana, Georgia and Peking universities shows that the OS X Keychain, which stores all your passwords, is vulnerable to an attack that …
When the group who discovered the issue informed Apple of the vulnerability on October 15, 2014, Apple asked for six months to fix the problem, though both OS X 10.10.3 and 10.10.4 are still vulnerable to the attack.
On the up side passwords stored are safe until you get hit with the exploit. Once hit though any new password put into Keychain is susceptible.