We have discovered that Splunk 6.0 is vulnerable to OpenSSL Heartbleed bug.
Is there any patch to solve that issue ?
This link should provide all the information you need. It was the first link when I google'd for "Splunk heartbleed bug".
....And if you need any help identifying servers vulnerable to the heartbleed bug, check out the Heartbleed Command for Splunk.
Blog post found here: http://discoveredintelligence.ca/heartbleed-command-splunk/
Direct link to Splunk app: http://apps.splunk.com/app/1762/
A hint for the future: first rule of forum use - search to see if your question has already been answered... This was answered, and fixed comprehensively within days of the original public revelations about Heartbleed.