Here’s the quickest way to check the installed Nessus version:

Linux

Run:

bash

nessuscli -v

If that is not in your PATH, try:

bash

/opt/nessus/sbin/nessuscli -v

The CLI output should include the Nessus version number.

Windows

Open PowerShell or CMD and run:

powershell

"C:\Program Files\Tenable\Nessus\nessuscli.exe" -v

You can also check the Nessus web UI under Settings > General for a “Nessus Version” field.

macOS

Run:

bash

sudo /Library/Nessus/run/sbin/nessuscli -v

or, on some installs:

bash

sudo /Library/NessusAgent/run/sbin/nessuscli -v

That will print the installed version directly.

One thing to know

If you’re comparing what Nessus reports with what you think is installed, make sure you’re checking the actual product binary or CLI output, because scans and inventory reports can sometimes reflect a different version source.

If you want, I can also give you the exact command for your OS in one line.