Sometimes, especially on Windows servers, it’s difficult to check to verify what version of Java you’re running while you’re making your rounds. If you don’t have a scanning tool to check it, here’s how to check your Java version by hand, even if the Java control panel doesn’t show up:
Navigate to C:\Program Files\Java\jre7\bin\javacpl.exe, run it, and click “About.” A dialog box including the full Java version number (both major number and update number) will appear.
If you’re running a major version of Java other than Version 7, the portion above in italics will vary.
You may also note one or more directories in C:\Program Files\Java that look like version numbers (such as 7u21), but that’s not a reliable indicator of what’s on the system now. It’s just a holding place for installation files, and indicates that someone at some point has installed or tried to install those versions. Keep in mind that update numbers are incremental but not necessarily consecutive. The current version as of this writing is 7u21, and the previous version was 7u17.
Check what version you’re running and check your system requirements before you upgrade something. I speak from experience.
And keep in mind if you have to run a specific older, vulnerable JRE, you can implement whitelisting to mitigate it.