Which OpenSSL Versions are Vulnerable and Whoi s vulnerable to Heartbleed? Heartbleed is only exploited where vulnerable OpenSSL software has been installed. Vulnerable versions are: 1.0.1 1.0.1a, 1.0.1b, 1.0.1c, 1.0.1d, 1.0.1e, 1.0.1f, 1.0.2-beta1 OpenSSL is installed mostly on the Apache servers and nginx servers. According to Netcraft,half a million trusted websites are vulnerable to this Heartbleed Bug