Among these are 2596 systems in Australia and 535 in New Zealand. The US has the most unpatched devices with 42,032, followed by South Korea (15,380).

The vulnerability, known as Heartbleed, is present in several versions of OpenSSL, a cryptographic library that enables SSL (Secure Sockets Layer) or TLS (Transport Layer Security) encryption.

The flaw would potentially allow attackers to monitor all information that flows between a user and a Web service, and could even decrypt past traffic they’ve collected, according to experts.

The problem, detailed in CVE-2014-0160, is a missing bounds check in the handling of the TLS heartbeat extension (hence the name 'Heartbleed'), which can then be used to view 64K of memory on a connected server. This allows attackers to obtain the private keys used to encrypt traffic.

The bug was discovered by three researchers from security firm Codenomicon and Neel Mehta, a security researcher at Google.

Most of the systems which are still vulnerable are offering https services. Not surprisingly, Apache leads the vulnerable systems with 51,983 hosts.

Amazon Web Services has the most vulnerable domains with 6375, while Linux 3.x is among the top operating systems affected.