Saabira Chaudhuri

US regulators said a vulnerability in banks' computer networks could have exposed sensitive information to hackers, and they instructed both small institutions and Wall Street firms to update their security systems.

The alert from the Federal Financial Institutions Examination Council said the "Heartbleed" encryption bug may have allowed hackers to access the private "keys" to banks' servers, allowing them to decrypt and view sensitive information.

The Federal Deposit Insurance Corporation, one of the members of the council, said it wasn't aware of attackers exploiting the Heartbleed flaw that became public in recent days but said banks should assume that their security systems may have been breached. Regulators said hackers may have accessed sensitive information without the banks' knowledge.